Chapter 2, mom abandoned their family for her affair partner. Affair partner didn't want kids so dad kicked mom out and proclaimed to take care of Ryota by himself. Ryota heard the whole conversation. Chapter 11, Ryota tells Akira that he found out that his dad is not his bio dad because of their blood type.
Now I'm curious if Suzuka's dad is the supposed affair partner.
oh that's right, I'd forgotten those details about his mom and the truth about his family situation.
Which makes him dipping out like this even more understandable.
If anything, I'm apprehensive about the resolution to this because someone like his mom
doesn't deserve his forgiveness, at least at this point. And Ryouta's the kind of character (and this is the kind of series) that would have him just magnanimously make up with her and act like "the past is the past!" because every point of conflict has to be tied up in a nice little bow and everyone becomes friends afterward.
Realistically, it should take years of effort on his mom's part to earn a spot in his life at all, much less anything approaching forgiveness or trust. And I don't know if
I trust the author to do the sort of betrayal she handed him--right down to his own dad not being his biological father--the requisite amount of justice Ryouta deserves, given how the other arcs of this series have gone.