I was observing two dwellers running into the back room after they did their little dance and at that exact moment a Radroach attack happened in another room. When the attack was over, I went back to the Barracks only to see the two dwellers back in conversation in the main room. It seems the Radroach attack cancelled the mating process. I waited about a minute and they started dancing again and another minute later they went into the back again and did their thing successfully.

Yeah, I think incidents in general spoil the mood. I've seen a fire ruin a romantic moment.

but apparently, raiders don't bother them one bit...