I don’t know what to do...

I am 18 and he is 20.

I am actually a young soul but he is... not so much.

And I realized that I close myself up.

I really love him (not in love maybe, but i love him) but I can’t really do it anymore I guess.

Whenever I think about breaking up, my heart starts pounding.

He’s been hurt so many times before, he got cheated too.

He keeps talking about marriage a lot, sometimes jokingly but whenever I say something negative about it he gets upset about it.

He said that “I feel like our relationship is going down, but I will do something to fix it. You should too.” But I am more like “If it goes, it goes. If it doesn’t, it doesn’t”

I am so confused...