Friends cutting me out?

I’m in college and I have a part-time job for the summer. I’ve gotten super close to my coworkers and we hangout a lot outside of work. However, my friends that I’ve known forever have been avoiding hanging out with me and it kind of saddens me. When I ask them if they want to hangout they ignore me or tell me that they’re busy. I don’t know if it’s because I’ve gotten close to my coworkers, but I just don’t know what I did wrong. I’m usually a sheltered person, so I’m having a lot of fun with my coworkers because I’ve never been so outgoing before.