should i be worried that my bf masturbates to other girls

Ask him to stop. Then again if you have been together for 2 years and you haven't asked him to stop when you first found out (how the hell did you find out?!) then it is doubtful he will change.
If it is bringing you down that much then you need to talk to him and get him to understand how you feel, and try make him see how creepy it is.

I hate to say it but the chances are your boyfriend is lying.

I already know that your mental response to this will be to think that I don't know you or your relationship, and only you can understand the trust you have with your boyfriend, etc. etc. This is because I used to have that kind of relationship, where I thought I had 100% honesty and trust with my boyfriend. He told me he didn't watch porn. I'd never even asked him not to, he just told me he hadn't, and didn't. I used to see people on TSR saying that men who say they don't watch it are lying, but I thought my relationship wasn't like that. We were together for four and a half years, and he kept up the lie. I found out by accident once and was absolutely staggered that he'd been lying for so long.

Not that there's anything wrong with a man masturbating. If you had a higher sex drive, I think you would struggle not to while he wasn't around. Let me ask you something - given that 99.9% of men who are in relationships still masturbate, do you think that none of their women pleasure them enough, and that it's their "fault"? Your stance is really illogical.

Nothing wrong with masturbating, however having said that, I find it somewhat weird that your bf does so to facebook pictures, it just comes off as creepy...real creepy.

PS: Have you considered giving him a "hand" while he's doing it on facebook, maybe you can be the one to pick the pictures this time...Would that help?

Why would any guy prefer masturbate to anything when you can have sex/get a bj ?
I've been dating someone for 3+ years and to be honest the only time I've ever masturbated is when we haven't seen each other in a while cause of travelling/being in different places.

Obviously I'm attracted to other girls too, and though I think my gf is pretty and I love her, there definitely are other pretty and more attractive girls out there. Sorry to say, but from my perspective at least, what your bf is doing is a bit weird.

How is it creepy? Loads of guys do this. If you were a guy, you'd almost certainly do it as well (and if you ARE a guy, I'm surprised you don't know how common it is).

I would be a bit creeped out if I knew random guys were pleasuring themselves over my profile picture on Facebook. I'm not the only one saying its creepy

They probably have done.

I don't know how to make him stop though. I think he has tried, when I confronted him. Either his willpower wasn't strong enough or I guess it comes to him naturally?

Hi, its internationally been changed to 'sulfur' now

I'm...honored?