Surely, you must be talking about a female partner (since you state you're 50/50)... trust me, this is not an issue for gay constellations
any time, it doent matter if you get a knock back, but remember yu can always give and hope to receive
make her cum with your fingers and/or tongue. when she's done writhing on the bed or floor or kitchen table, just come right out and say "i'd love it if you'd suck my cock" if she's already fucking you, chances are she's not too prudish to suck your cock.