I am getting a opinion that that Risa in terms of perversion is much more dangerous than Momo because if Momo is as perverted as people think why doesn't she outright rape him like in the series of OmamoriHimari they did the Main character of that series a favor all the girls except the Main pairing outright raped him in his sleep.
I think that this might be what is required for Rito because he is similar to the Main character of OmamoriHimari in some aspects.