He already addressed this. He said the Sejin wasnt the gift he left for his brother. His brother being the degenerate he is went to the house and happened to come across Sejin, it wasnt supposed to happen. The misunderstanding came when Sejin THOUGHT that Ido sent the brother to do that purposely (again, Sejin WAS NOT THE GIFT) But he believed what his brother said and basically told Ido "Hey me and your brother fucked liked you wanted." (It was actually grape) and Ido took that as "OH so you fucked my brother." And did his unspeakable act in retaliation. Once again, Sejin was never supposed to be the gift. The whole thing was just one huge cluster fuck

I can’t move on till he says WHY TF HE LET HIS BROTHER RAPE MC WHILE HE WAS IN HEAT THEN WHEN HE FOUND OUT HIS RESPONSE WAS TO RAPE HIM AGAIN BARLEY 3 DAY AFTER HIS BROTHER DID (KNOTS HIM) MARKS HIM, AND THEN ASKS IF HE WAS LIKE THIS WITH HIS BROTHER *throws up irl* EVEN WHEN HE FINDS OUT HE GOT PREG HE STILL DOES NOTHINGGGG TO HIS BROTHER AND JUST IGNORES AND SHUNS MC(;_;) PLUS ALL OF THIS ON THE FACT THAT HE TOLD HIS BROTHER IT WAS A “gift” like AHHHHHHHHH(´༎ρ༎`) not to mention that was just the worst he was doing