I wonder if Rei know what the girls actually did to Youta and why he been insecure so much over the years from what we know so far he would he furious without a doubt I mean a fangirl that know the truth about Youta even feel terrible and try to save him from them in previous chapters
Honestly, I don't think him or the rest of the family know what is happening. We have seen that the parents love both of their children and don't actually play favorites with them (at least how it has been presented so far), but our MC still has an inferiority complex of his own making (which is understandable). We have also seen that his brother cares about and loves him too. So, with that, if he had said anything to ANY of them, I am sure that they would have done something about it, but odds are higher he never said a word to them so they are oblivious to what happened.
I can already see it.
Hojo wanting to do something special for Youta, so she goes to the person most likely to know him best.
Youta sees Hojo hanging around Reiya all happy smiles (prolly because she's talking and learning about Youta), gets the wrong idea, and gets crushed.
This is most likely what will happen, and from MC's perspective it will be devastating considering everything that has happened to him beforehand. I am sure they will work it out, but he is going to be super depressed for a bit and it is going to suck to see him like that...and the fact there will be no interactions with Houjou during that time.