In that era, dating consisted of sitting side by side in a field, waiting for the Sun to set, so that the drive-in movie could start. They only lacked the autos and the motion picture technology. Oh, and popcorn.
That assumes that Neandertal and Cro-Magnon people sat peacefully together, rather than engaging in battle for the women and the local hunting grounds. Maybe they did, maybe they didn’t.
If they fought when they met, the raper would be of the race of the victor, and the rapee would be the race of the defeated.
Maybe someone has a lead on this through salvaged DNA and maternal mitochodria. Not my field.