I Am Afraid Of Losing A Friend

My childhood best friend stopped talking to me once I was put into our school district's accelerated learning program. I had to switch schools and I lost all of my friends. Everyone at the new school teased us for being nerds and it showed me how quickly people will abandon you in this society. Fast forward a dozen years and I'm a freshman in college now. There's a group of kids who I thought I was friendly with, but they hang out all the time and deliberately exclude me. My best friend (we'll call him Mark) likes one of the girls in that group. Recently he told one of her best guy friends that he's into her and this guy friend promised to invite him to hang out whenever she's around. Mark said he's going to start getting dinner and doing homework with them most nights. I'm afraid that he'll end up ditching me just like my last best friend did.