What makes you interested in someone enough to pursue a friendship/relationship?

I feel incapable of being interested in people enough to pursue any friendship/relationship with them. I just keep thinking I'll meet someone I really like someday but doubt it'll ever happen.

I'm an introvert and enjoy spending time by myself, friends aren't a necessity. Though, if I meet people, I will always make an attempt at getting to know them. But, I'm usually disappointed once learning more and don't pursue anything further than being acquaintances. Despite this, people typically like me a lot once they get to know me and want to spend more time with, and talk to, me. I feel bad because I never reciprocate.
What makes you interested in someone enough to pursue a friendship/relationship?
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