That should be 'unattractive'.
There's also same sex couples, which would be the most difficult I suspect, because with hetero couples there is a set gender specific guideline, it's not always used, but it's there to fall back on.
So if both are Introverts, and both the same gender, then it'll all be very confusing as to who does what, as without the male/Extrovert they have to just find what works, if anything, for them specifically.
Ugh, it's depressing really.