What would solve the "moral" dilemma occurring here would be to conceptualize the idea that God does not exist. Makes it easy huh?
The thing is I respect Crumpet for having the guts to end the relationship before pursuing another, male or female. What is done in the privacy of ones own bedroom, closet, car, dinner table, kitchen, garden, hiking trail, department store dressing room is their god-damned business. Isn't judging a sin? Yeah. Thought so. My balls. Your misplaced judgment is breakin 'em. I say who the hell are you?
This is why I can't stand most Christians. You profess to love thy neighbor, to love thine enemies, yet that rafter in your eye is obstructing your vision to the extent that you cannot see that you have promptly pushed your God off of his throne and began judgment of a situation/desire/experience with ZERO perception of.
Crumpet, do your thing. We've got your back. Live your life. Be happy. Love whoever has the smarts and the perception to love you back. If I were in the UK, I'd get a wig, a shave and a tuck and we'd make it a date. Do your thing.