All's fair in love and war. I wonder if that would be a good pool.
But that's not what the expression means. It means "it's fine to fight dirty", so actually demanding that others "play fair" in love and war would mean that there are things that aren't fair in love and war.
Do you... want to have a match with Ooi?Hmmm... Yeah, kinda.Ooicchi's my friend and all,...I see.In the truest sense.so she always holds back just a little bit, see?In battle, or in love.I just wanna try having a rumble with a serious Ooicchi, 'ya know?I want us to be on equal terms, yeah?