I know this might sound like a stupid issue, but I really am too nice to people. Even when someone offends me, makes fun of me or simply abuses me, I still treat them nicely and remain polite no matter what. I am not able to ever stand my own ground, I am not able to say "no" and I let people come too close to me even when I am uncomfortable with it.
I am unable to set the boundaries and stand up for myself, no wonder that I feel like people don't really value me or take me as their equal because I voluntarily lower my position.

I can't count how many times this caused me issues, mostly in a romantic way and I end up in a relationship with people I don't even like just because I am too scared to tell them the truth and hurt their feelings. Like the last time I was trapped in a relationship for over a year simply because I wasn't able to tell the guy that I don't really like him.

For me it's almost unimaginable that someone actually wouldn't like me. I don't know why but I am obsessed with fitting in and finding people who'd like me the way I am, but I usually end up as an outsider anyway.

How can I stop this nonsense? What might be causing this?