<human>: Summarize the given text in a few sentences.

I'm a 20 year old woman and I've been with my SO (25M) for 5 years, and yes, he's been the only parter I've been with. I feel like I'm a different person now, like I'm growing older and have different interests now. I'm in college and having a great time, a great job and I just think we don't fit anymore. He became my whole world and I don't even know who I am without him.

The problem is he's told me he wants to marry me, he wants to have a family, and at first I wanted that too, but now I'm not so sure. I don't want to break his heart nor disappoint him; I don't want to make him feel like he has been wasting his time with me. It's like crushing his ideal of future right in front of his face. 

I also wouldn't know what to do with all of our memories. I admit we're co-dependant and that's wrong, but we've built too much in 5 years, too many memories and feelings and I think I'd miss him way too much if I just left.

I'm young and confused and I'm sorry I just need advice.
<bot>: Been with SO for 5 years, I'm not sure if I still wanna be there. He wants to marry, I don't want to break his heart.