User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-104.7.80.176-20150603035954/@comment-98.227.238.52-20150603194854

I still think Rias should have seen the signs of what her antics was doing to Ise. Not to mention the Gremory family is known for great affection I guess Ise would believe that Rias was just being affectionate with him. It didn't mean it was actual feelings of love. And Rias didn't even know she was going fall for Ise. And I don't think he ever thought she would either. She is his master and the next heir to her clan. I guess he didn't think he was really qualified to be her boyfriend.

And given how flirty she and Akeno are with him and how much they love to tease him, I'm sure they gave him a lot of mixed messages.

Not to mention Rias' mother and father told them to treat the Gremory house as their second home and they asked him to call them father and mother. Sirzechs and Grayfia said he could call them big brother and big sister. With what they said they could be just saying that he could treat them like family.