Caught my girlfriend with another guy

So me and my girlfriend are both second years in uni and have been together since the start of uni. The first year we were together was perfect and we did everything together and were madly in love. This year I still love her just as much, but I feel she loves me less and less. None of our friends know that we're in a relationship, but they know there's something 'more than friends' between us. We live together (just us 2) in a flat and have done for the whole time we are together. She is a very flirty person and she likes flirting with people and she told about how she was with other guys while she was with her last bf of 5 years. She says she wants to change and I honestly believe she does, and she did for the first year, but if the temptation is there I think she can't resist, no matter how much she loves me. She develops a crush very easily and so if a guy likes her and is nice to her, she starts to like them too(not love them, just like them as a crush) . She's texted other ppl and allows them to flirt with her, but she doesn't flirt too much with them.

The guy I caught her with is our friend which we've known for about 6 months and they've been texting a lot but she said they're just friends, but I know they like each other. I came home early from a lecture a few weeks ago to surprise her and when I entered my flat, I caught her with him. She says she wasn't doing anything, but she looked very guilty and she said he only came to drop off her text book which I gave to him earlier that week.

Last night that guy, who says he's in love with her, (he doesn't know she's actually with me, but knows there's something there ) came round because he's 3rd year on the same course as her and she needed help. I trusted her not to do anything because she said she didn't like him so I left them in the dining room and I was in the other room watching a movie. When I heard the talking stop for a while I went to see what was happening. I caught him lying on the bed with her on top of him. She says they weren't kissing but it definitely looked like they were, and he has hickey s on the side of his neck. She was honest with me yesterday after I caught her and she says I'm perfect for her and everything she wants, but she likes him, but not sure how much. She says she doesn't trust him as he flirts with lots of girls and she doesn't know why she likes him.
What should I do? I've been trying so hard to trust her again after I caught them together that first time and after she denied texting other guys, and now I see this? Right in the room next to me! I love her more than anything and don't want to break up,but I don't know what to do because I know she wants to change. I've spoken to her about how it hurts me and she says 'you deserve someone better'. But I want her, no one else, and I want to help her change, but it seems like if the change gets too much, she stops trying so hard and goes back to her old ways of flirting and being with with guys. I want to believe this is just another crush, but I've never seen her actually physically do stuff with the others, only text. That's why I feel this one is different. I'm so lost and torn and I don't know what to do.

Let me get this straight...

Your girlfriend of over a year regularly flirts with other people, gets caught laying on top of someone else, leaves a hickey on his neck, lies to you on a constant basis and, as a cherry on top of this disaster of a cake, practically nobody actually knows you two are together, giving her free reign to do whatever she wants. You're okay with all that?! Do you really think you can stomach that for a few more days or weeks, let alone indefinitely?

Listen to me - I know it seems difficult at the moment, I know it does, and that nothing makes sense, but you need to get away from this person. You need to get her out of your life, recover from her lies, games and tricks, and find someone who will care about you and treat you way nicer then she does. It will be infinitely hurtful in the beginning, but in the long run, you'll spare yourself a tremendous amount of pain, jealousy, anxiety and heartbreak.

Better to slowly back away now before you end up on the Jeremy Kyle show with her...

She only started doing l this recently. I was always pretty relaxed about how much she talks to other guys because in the first we we trusted each other completely. The way she talks is flirty in general, so when she used to talk to them last year she didn't talk to them much because she knew what would happen. I don't know what could have started it. We were perfect together, then something changed over summer (we didn't see each other for 2 months due to her being from another country). Then it was fine for the first few months. Then from November onwards it's been getting worse and worse. I just want things to go back to the way they were and get this sorted before it gets too late
I realise that she isn't a good person right now, but I know she can be, so I don't want to leave her just yet.

Let me get this straight...

Your girlfriend of over a year regularly flirts with other people, gets caught laying on top of someone else, leaves a hickey on his neck, lies to you on a constant basis and, as a cherry on top of this disaster of a cake, practically nobody actually knows you two are together, giving her free reign to do whatever she wants. You're okay with all that?! Do you really think you can stomach that for a few more days or weeks, let alone indefinitely?

Listen to me - I know it seems difficult at the moment, I know it does, and that nothing makes sense, but you need to get away from this person. You need to get her out of your life, recover from her lies, games and tricks, and find someone who will care about you and treat you way nicer then she does. It will be infinitely hurtful in the beginning, but in the long run, you'll spare yourself a tremendous amount of pain, jealousy, anxiety and heartbreak.

Better to slowly back away now before you end up on the Jeremy Kyle show with her...

I just want things to go back to the way they were and get this sorted before it gets too late

Reading things like this only enforces my viewpoint on staying single through uni, that's the kind of thing I'd hate to be going through.

So me and my girlfriend are both second years in uni and have been together since the start of uni. The first year we were together was perfect and we did everything together and were madly in love. This year I still love her just as much, but I feel she loves me less and less. None of our friends know that we're in a relationship, but they know there's something 'more than friends' between us. We live together (just us 2) in a flat and have done for the whole time we are together. She is a very flirty person and she likes flirting with people and she told about how she was with other guys while she was with her last bf of 5 years. She says she wants to change and I honestly believe she does, and she did for the first year, but if the temptation is there I think she can't resist, no matter how much she loves me. She develops a crush very easily and so if a guy likes her and is nice to her, she starts to like them too(not love them, just like them as a crush) . She's texted other ppl and allows them to flirt with her, but she doesn't flirt too much with them.

The guy I caught her with is our friend which we've known for about 6 months and they've been texting a lot but she said they're just friends, but I know they like each other. I came home early from a lecture a few weeks ago to surprise her and when I entered my flat, I caught her with him. She says she wasn't doing anything, but she looked very guilty and she said he only came to drop off her text book which I gave to him earlier that week.

Last night that guy, who says he's in love with her, (he doesn't know she's actually with me, but knows there's something there ) came round because he's 3rd year on the same course as her and she needed help. I trusted her not to do anything because she said she didn't like him so I left them in the dining room and I was in the other room watching a movie. When I heard the talking stop for a while I went to see what was happening. I caught him lying on the bed with her on top of him. She says they weren't kissing but it definitely looked like they were, and he has hickey s on the side of his neck. She was honest with me yesterday after I caught her and she says I'm perfect for her and everything she wants, but she likes him, but not sure how much. She says she doesn't trust him as he flirts with lots of girls and she doesn't know why she likes him.
What should I do? I've been trying so hard to trust her again after I caught them together that first time and after she denied texting other guys, and now I see this? Right in the room next to me! I love her more than anything and don't want to break up,but I don't know what to do because I know she wants to change. I've spoken to her about how it hurts me and she says 'you deserve someone better'. But I want her, no one else, and I want to help her change, but it seems like if the change gets too much, she stops trying so hard and goes back to her old ways of flirting and being with with guys. I want to believe this is just another crush, but I've never seen her actually physically do stuff with the others, only text. That's why I feel this one is different. I'm so lost and torn and I don't know what to do.