[Does it make a strong difference to him? No, not really. It would feel more like denying the truth, which would be disrespectful to both of them.]

Dad, then. He mostly wanted to make sure he wasn't... stepping on any toes, I guess? 'Cause him and my mom decided not to be exclusive ages ago, but he didn't want to assume anything about me and how I felt.

[A thoughtful frown tugs at his lips.]

I don't know if he's more serious about it or I'm just missing something here, but - I don't really see why it matters. You can't actually have relationships like that, so nobody's moving in on anybody's territory, right? [Action-oriented vs emotion-oriented processing at work again.]