Girlfriend is leaving

I've been with my gf for 8 years. We started dating in high school and are about to graduate college. We have been fighting for about 3 months with her saying she is unhappy with the relationship and does not give me a real reason why she is unhappy. Last month we broke up and she hooked up with a guy from one of her classes that she ran into at a bar one night while out with her friends. I found out and asked her about it. She admitted it and claimed she wanted me back. After 3 weeks of trying to fix things I assumed things were good. We both seemed happy and I left her place two hours away where she is living for the summer. Two days later she says she was just trying to make it work again and was still unhappy. She says she loves me still but wants her space. She says this is the best time to take space and she wants to be done. Another thing I should add is the guy she got with is over 15 hours away so I know he is out of the picture. Is there more to what she is saying? Does she really want to be done after 8 years of dating? I don't know if I should move on like she is claiming she is trying to do or what is her real plans? Thanks for the help.

Loves you but still wants her 'space' = the relationship is doomed -she's just trying to candy coat it. It's similar to 'we'll always stay friends' which is also complete bullshit.

People change a lot between their mid-teens and early-20s. The two of you have probably changed to the point that you're not compatible anymore. Move on and date other women. Maybe she will come back some day, but you need to get on with your life for now.

She's growing up and looking to see what else is out there. I think the relationship has run its course and you are going to have to be the strong one and say "enough". She's jerking your strings and you are letting her. Time to move on, I'm afraid.