Why is he mad at Rena because his mom decide to seek others options(her father) to sleep with. Did Rena tell her father to go to pound town on his mom?...But doesn't mean I like her character at all...Just saying.
To plant seeds of doubt (which seemed to have worked with how dazed she was) and to have some sort of feeling of superiority over Aoi. Especially with how obvious she's still into Keita she is. I mean, it was obvious last chapter but it's even moreso now.
Everyone else: locked in on the relationship drama
Me: "Why the hell did the author need to use a weird, CG-ish clip-art basketball instead of just drawing one? It can't save that much time to offset how incredibly jarring it looks."