Suga asked his mother to leave him alone and wait for those 20 minutes in hopes that some miracle would happen. Everything he went through vanished the moment he made up with Chaeyoung but it didn't last longer than a day for his mother to show up and destroy everything. She arranged his marriage with some girl she knew and threatened him. Suga expectedly refused but the moment his mother showed him what she had against Chaeyoung he gave up and refused to see his mother destroy the one he loves. His mother along with his father fabricated some evidence that Chaeyoung is involved in bribery and kidnapping and Suga was left with know choice but to believe that and leave her.
He knew Chaeyoung would hate him to the core, he knew that would devastate her but he was helpless. If that was the only way to save Chaeyoung then he had to do it.

The wedding ceremony started and Suga's legs refused to take any step out of the room. He knew that there's no going back, once he gets married , everything will be over. There'll be no more him and Chaeyoung. A knock on the door was everything he wished to hear to get him out of that nightmare. And it happened, a hard knock made him snap out of his trembling state and the next thing he knew was Mino holding his shoulder and shaking him.

"what's wrong with you?" Mino said showing deep worry.

"I can't do this Mino, I just can't marry anyone else like this"

"well, you don't have to do this" Mino said "You can