Only guys in a relationship talk to me

Hi everyone,

I'm 17 and every single guy that comes and talks to me is in a relationship. This is exhausting because I am not aware that they have someone and they talk to me like they are single and 'want me'. They flirt etc and I don't fall for guys that just flirt when they talk to me but these guys actually show an interest in my personality, life, interests etc until after sometime I find out they have someone and when I ask them about this, they are freaking *******s to me or don't give me an answer.

Btw, when I say 'them' I don't mean that I talk with several guys, I mean in a spread amount of time. I'm really tired of this, I don't seem to find someone that I like and likes me back aka doesn't treat me like **** and I feel really bad about myself that only guys in a relationship talk to me and that i'm indirectly and probably directly sometimes hurting the person they are with... why do they even do this?

And they guy I love is my guy best friend that is also in a relationship after we broke up a few months ago yay for me.