Role Confusion

Question: If a lesbian couple gets onto a crowded metro and there is one seat left, which of the two gets to sit down?

This is the exact situation that happened on the metro the other day. A couple was arguing about who got to sit down in the seat next to me while the other one stood.

I guess if I was a part of a lesbian couple I would make sure that we decide these things beforehand so we don't make a scene in public. How embarrassing for them. Of course a lot of things would have to be very different in order for that scenario to involve me anyway...