What should I do I think my girlfriend is going to leave me ?

If you’re concerned that there is a problem, the mature thing to do is to approach her about it (yourself, not your friends, not WITH your friends) when you both are alone and have a length of time appropriate to discuss the issue in depth. Between classes is not a good choice, neither is at lunch. I would see how things pan out, and then call her after dinner, or, better yet, get together after dinner. Let her know that you suspect she may be wanting to break up. Let her know your rational reasons why you’re feeling insecure about it (you ‘just sensing it’ isn’t a rational reason- her not returning your calls at all and ignoring you in the hallway would be a good example). It’s OK if she does break up with you, you need to know that. It’s ok for you, and it’s ok for her. You’re teenagers, this is by no means the greatest relationship of your life, and it will by no means be expected to last forever. You’re dating to have fun and because you like each other’s company- if either one of those things changes for one of the people in the relationship, it stops being worth the effort. You’re not married, you don’t have to stay together. In fact, breaking up before it gets ugly is often a great way to salvage a friendship. Truth is, if she doesn’t want to be with you, you can’t make her. You can guilt her into it, but she’ll resent you. But try talking it out- see if there is a behavior you can change (not a personality trait- a BEHAVIOR) to make things work better. There may be nothing wrong- we girls can act aloof unintentionally sometimes. You wont know until you talk it out in a calm, loving, mature manner. Good luck- I hope things work out for you.