Recently, I read a paranormal novel about a romantic couple fighting demons. During the action scenes, they were so busy fantasizing about the other’s crotch that I wondered at the brains and survival skills of these people. In the real world, a fighter who is busy thinking about sex before and during a fight is a dead fighter.
The pace was also ruined because the constant sexual elements and sexual introspection distracted from the peril.
Brief bits of body language--a touch, a smile, or caress, as well as brief snippets of romantic dialogue can keep the sexual tension and caring evident without bringing the story to a dead halt.
Wait until a lull in the fighting to put your couple in a safe hiding place where they can repair their wounds and chase each other around the bed.
The important thing to remember is that even in a romantic story, sex shouldn’t be paramount in action scenes, but after the battle is won, all that extra adrenaline is a nice appetizer to sex.