Should i move on?

Me and my girlfriend have been dating for 4 years soon. At first, we were very sure that we wanted to be together. We were so comfortable together and had regular sex. This was our senior year. When i left to go tt college everything was still fine regardless of the long distance ( 3 hours). The next year i left college while sse attended a college 30 minutes away and thats when things went downhill. She started hanging with more guys and even went out way more. She wont let me go out with her or invite me anywhere, shed rather do it with her friends. We started having sex less and she never wants it anymore or talks about it. She hasn't engaged in a sexy convo this year yet. We see each other 4 times a month for like 6 hours max. She's a busy person, but she makes time for others. SShe gets really defensive when i bring this stuff up. In the summer, she flew to another state to see a guy friend I've never met. She doesn't see anything wrong at all with what she does. She says she loves me and doesn't want a break but shows otherwise. What should i do? Give her a chance even go through its been going on since February or move on?