deevee, you’re making this tougher than it has to be. There’s no need to even entertain a question of “who comes first”.
Children have certain needs and a responsible parent will see to it that those needs are met.
Adults have needs as well, and if there’s to be a meaningful relationship between adults, they must meet each other’s needs. There’s enough time in a day for both.
Sometimes children will make demands. Telling them “no, we’re not going to a movie tonight because HE (or SHE) and I are going out” doesn’t mean that the children aren’t being loved and cared for. It just means that they aren’t calling the shots to the extent that they’d like to. Nothin’ wrong with that.
I never saw the need to try to decide Who Comes First. There should be love enough for all, and compromise when necessary.