You might think that this is not an excuse for him to do such a thing.
However, when the girlfriend starts to control their boyfriend to do what they want like what Seo Ye Ji did to him, it is an acceptable reason.
You don't know how bullshit and ridiculous it is when you have a girlfriend like that.
Even drama shows a lot of this shit. The man is just scared of her.
Is just like a wife getting jealous of their husband when they are with cute girls.