The only way I'd accept a love interest who can't fight (like Monica) is if she gets powers shortly after her introduction and gets to work becoming the warrior queen T'Challa needs. That's a unique arc to put a character on and prevents them from being a damsel in distress, kinda like Pepper Potts AKA Rescue. Other than that I agree with everything you said, in between all the heroic stuff build the romance and then finally make it official and have them continue as a unit.