This is a female colleague of the same age (early 20s) who he's known for about a year now and sees pretty much every day at work. They don't work in the same dept. but he wants to move to hers because the people are funner in his opinion. However, they take smoking breaks together and eat lunch in a group.
In terms of personality, she seems very outgoing, bubbly, jokey, and a party animal. They both like to drink and smoke (including cannabis) but I'm quite different myself.
For quite a few months now, they (including her) have been going out drinking on Friday nights after work. He usually came back by midnight, never really later, and always texted me(even though I never asked him or expected him to)
So last time when he arrived at 7am after giving me no news whatsoever (i'd been trying to call and such) you can imagine my panic. He told me that they had been at her place (but as a large group) for 5 hours because she lives quite close. I found out a week later that he'd been lying and that it'd been just the 2 of them for 5 hours (he'd told his friends this but not me). He tried to reassure me that there was nothing to worry about, it was just friendly etc. and I felt better.
He talks a lot about her, it sounds like they have a lot of banter and they're constantly teasing each other. He is always smiling and laughing when he talks about her and tells me a joke she said or something like that. They went out as a group on Friday. I had gone to bed at midnight, and was awoken at 2am by him coming in. He came into the room and told me that she was in the living room, because she 'couldn't get back' (I later found out that this was a lie too) and that she'd get a taxi back soon.
I was half asleep and in pjyamas so did not want to go out, but could hear them talking and laughing. An hour later they left, and he came back alone 2 hours later. Apparently they'd been on a walk and had gotten something to eat.
I tried to not seem jealous; asked questions about her etc. and I asked whether I would meet her (he said, maybe). And again he had lots of funny stuff to tell me about her.
I just don't see it necessary for him to be inviting her alone for a few hours, especially when i'm in bed. They have just spent 8 hours togrether at a bar. Physically, I've seen pics of her and she's his type. Recently we've had a lot of problems and really bad arguments, and he's not as affectionate. He told me it maybe wasn't working out.
I'm scared he is into this girl and vice versa. Do you think I am over reacting? Does it sound suspicious? Thanks