Why won't he ever open up to me?

I dated this guy for about 9 months and fell in LOVE with him like crazy. He had some trouble in his past with his parents and ex-fiance, yes fiance, and just won't open up to me at all. I've tried everything possible, by opening up to him first, making him feel 100% comfortable around me, keeping the smallest things about us between us, etc... But nothing seems to be good enough for him to express how he feels toward me. He claims that his parents were going through some stuff and he got caught in the middle of it and his girlfriend at the time just wasn't there for him and kept everything he felt to himself, and he claims that's why he does that today is because in his opinion you can't rely on nobody but yourself. I've tried everything to prove to him that I will always be there for him no matter what and that he can express himself to me anytime, but yet he never does. Why might this be?

Also, why is is that he is more open with complimenting or being sweet to me now that we are on break, for example, he tells me more now that I'm beautiful, hot, and have wonderful boobs, and gorgeous eyes, and is amazing, etc... but when we were together
these words rarely came out of his mouth?