Spoilers from a Poor MTL

They haven't broken up... At least not yet. There seems to be some slight angst on the horizon. It seems like it has to do with the seme's go with the flow attitude with relationship and feelings.

The issue with the sister is that the seme knew who his sister was and didn't let him know about it because he didn't think it was relevant to their relationship. He also accidentally outs him to his sister since sister and send have talked about their relationships before and she figures it out when brother ran into seme and sister during a business thing. Uke isn't happy because the seme doesn't think the things with his sister are important for their relationship. Sister is pissed because she is the last one to know about uke and seme. Uke thinks she's disgusted with him. While working through the misunderstanding, sister yells that she's a lesbian... In the street. The brother and sister start getting super embarrassed and uke tries to run away while sister chases after him. Sister's gf (who also knew about uke and send) shows up and yells at them to do this shit inside. They go to gf's apartment and she says yell in here since the room is pretty much soundproof. Lol It's actually quite a funny chapter.