Well, from your perspective, yeah, definitely creepy. If my partner were to treat NRE in that way, I'd be pretty annoyed.
But NRE is completely different than that. It's taking joy in your partner's happiness....and a new partner for him/her brings a whole new kind of happiness.
It just so happens that when you're happy, that tends to rub off in the bedroom as well. Depressed people don't typically enjoy physical intimacy.