Hi, Katie...I don't have a facebook membership, but I can attest that the Internet sure opens up a whole new can of worms when it comes to trust vs. paranoia. It sounds like your beau just likes the many venues for social exchange offered on the Internet, and since he features pictures of the two of you on his page, stating upfront that he is in a relationship, it sounds as if you will need to try to trust him. It doesn't sound like he is willing to remove himself from Facebook to accommodate your insecurity, which may be well-founded. I agree that many girls/women won't give a hoot whether he states that he has a partner. Therein lies the abilty to trust him, and decide whether he is worthy of your trust.
Patty