User blog comment:Ixarising/Favourite couple./@comment-4547267-20131213223252/@comment-16281343-20131214020718

The fact that he lives with the girls, but not the whole school, only close friends.

The fact that he is dating Rias, not quite. Some heard Issei calling Rias by her given name without honorifics giving the idea that they are close, but it has not yet escalated for it being a rumor of them dating.