He DIDN'T have choice by this time. SiYeon has been sick for over a year, and he's been struggling to pay for the meds and their living expenses. He doesn't have and probably couldn't afford a baby sitter, and he has to watch over his son and care for him single-handedly while overworking to pay for the bills. His son needs better meds. He HAD been doing well until a year ago. DoYoon waited for him to come for help, but he never did. So DoYoon now swooped in. If not, YeJun would have continued on living this way. Also, the alpha dad has access to better meds and can help provide financial and physical support (DoYoon and staff can watch over their child) as well. It's rather unfortunate that he's forcing YeJun to retire from working though. That part really really sucks. But at the same time, it DOES give him more time with their child, and idk, more sexy time, according to DY.
I'm sorry to say this but I hate that omega types like if u don't harder to help yourself and your child when what was the point of running away that just bother me.
oh and alpha is a also trying to play Father but their types always get redemption arc so we will see how he changes