Dont know what to do. Tell me your opinion... i would like to know

Hello to everyone ,
I am 21 and she is 19. we are together since this summer (july). All this time things were going very good. We had sex and time for each other. Now she is busy because she is studing for her exams , those that are critical for passing to a university. We live about 1 hour away and its not so easy to come in touch everyday. We were dating 3 times per week and now 1 per week or 1 per 1,5 weeks. Lately...(1 month) we dont have sex because we dont have a place to go for this so the only way is my second house but its also 1hour away and there are not so good public transportation. This last month she dont talk to me like before ,she dont call me like before , also dont talk to me sweet or trying to be cute as she were. We talked about it and she told me that she is a little bit bored with all this and she puts first her lessons . I agree but she could have both. We talk with spaces. I mean she tells me goodmoring and then we talk again late at night and maybe she calls or i do .One day we talk each other and I told her .."do you want to continue this relationship?" she said yes and from then she isnt like before , exited. I dont know what to do. I love her but she acts immature and she dont take it serius. Am i overreacting or what? Should i broke up with her? make her jealous?let her space? I would like to know what do you think why to do any of these. Any suggestions?