Is it normal for my girlfriend to have many of her college professors as facebook friends?

Ive had some suspicions about my girlfirend in the past. recently she friended ,me on facebook and i noticed she had about 10 of her male professors as friends and they also post to her wall very frequently, i even saw a photo of her with her professor at a local sports festival. i asked her about it, and she denied it..but the photo was clear as day. another professor had a post asking her out for a drink and she accepted it. i asked her, and she said i was reading too much into it. another post i saw a photo of her with a professor at a local rock concert. next thing i know after begging for me to add her on facebook, once i do.she then deletes me from facebook. she then said" why dont you trust me?" I also saw a phot of her on NY eve with a professor...she claimes she ran into him by accident at a local club. i hate to say this...but is she a whore? we have hot sex, but do i need to stay clear of her. it seems at times, she only contacts me when she needs something or a favor. is it normal for a female student to have this much contact with her professors or is this a whore?