Before I left he used to tell me how much he loves me and he used to text me all the time, but I went on vacation and the day after I got back I went over to his house and he was acting like he wasn't being himself. He was acting completely different and kind of distant too. He hasn't texted me all day and we're supposed to be doing something tonight, help!

Don't waste anytime with this situation. His change means something so just confront him about it. Ask him directly what is going on and get your answers! If he avoids it but continues to act strange, leave him. Tell him, you're too old to be playing games. I've been there before and trust me, chances are he did something while you were away but only he can tell you.