People say crazy things when making sex. I dunno.
but he mentioned in previous chapters that he think he might be in love with him? i thought the build up made sense, but it's not like keith is /happy/ that what he feels is love.
I mean it's somewhat implied Keith is jealous here that Della was with someone else and he knows he's been craving Della. Also in a manipulative way Della has been begging Keith to love him. If he thinks Della is slipping away the easiest way to bring him back is give him exactly what he wants...orat least Keith thinks that's what he's doing.
What? That's such a random confession like genuinely what could possibly make you spout that nonsense and why should we the readers believe that it somehow should've come up to this (as in how the fuck could he have fallen in love so fast and easily with no building up) /gen question