My fish are out side. I always age my water .... cycled? .. IDK. Anyway, since I don't want mosquitoes in my water, I always leave one (usually male) in it. And introduce the female when I think the water is ready.
IME, once a pair is flirting (considering both are in top health) you shouldn't separate them. They will eventually spawn. Sometimes (very seldom) it may take them a week to spawn (specially if temp is low). But they will spawn. Just make sure none is hurting the other..... like your pair - fairly peaceful.