<human>: Can you condense the text into a few key points?

I'm 22 (f), he's 27. We've been together for 9 months and things are going great. The thing is, he's got an fb account and I do not. We have a mutual friend he's fb friends with and we go on her account together so I can check out some information on a school group I'm interested in. Unfortunately, on her news feed, I see that he's been liking several girl's photos. Bikini pics, pics with cleavage showing, etc. I trust him, and I know he loves me but this bothered me especially when he says I'm beautiful and things of that nature. All these nice comments seem insincere now. He's a sensitive guy and I know he'd get upset with me if I bring it up. If you think I should bring it up, what's the best way I should do it? I feel this might be petty so I wanted to get an outsider's opinion.
<bot>: I don't have a fb, but I found out that my bf is "liking" his female friend's photos (esppecially bikini, ones showing lots of skin). What should I do?