I date/have sex with who I'm physically attracted to. Otherwise I'm OK if we just stay (non-sexual) friends. Us having stuff in common doesn't make me horny for them or want to romance them.
If we have nothing in common because of an age gap, then the sexual relationship becomes a reason to learn about them. As long as we agree with each other on politics.
That said I have no expectations, admittedly atm all I've been getting is one night stands every once in a while and I'd like deeper relationships (I'm poly). But fuck maybe I just wont get one. shrugs I'll just keep trying until I get one.