What do you think is wrong with me?

Oksy so I am 16 years old. I can't seem to find a nice, steady boyfriend. The same thing always happens in my relationships. It's always the same process. I find a really nice, but not necessarily "cute" guy, he ends up liking me, I decide to give him a chance, we date for a few months in which I always end up really liking him, he ends up dumping me for someone else. I really don't know what's wrong. I try to be the perfect girlfriend by always looking nice, being fun to be around, giving him his space but also always being there for him. (Not to toot my own horn, but i'm also quite a good cook. lol) But seriously, these guys are the ones that liked ME to start with. I just want to find a nice, steady, boyfriend like the rest of my friends. :(