Dovahkiin (male or female) discovers that the person they are cheating on their lover with, is the same person their lover is cheating on /them/ with. Threesome, hilarity, drama, or a combination ensue. LIs can be either male or female as well.
I totally did not rip off an entry to FMyLife, nope.

Squicks are anything bathroom-related, and that's about it!
OP has a weakness for mer (this includes Orcs), also. c:
Go wild~!