Big fail. Would be hard for Sungji now. and even if seana doesn't fall for bumman's advances, I don't think it'll be possible for her to appreciate the effort that at least Sungji tried to save her.
Also, in a way is bumman somehow wingmanning Sungji? He's actually kinda giving him more of a push by being a villain. Like as he says, if someone else is vying for the person you like, you'll fight in jealousy rather than cower in fear. So its kind of giving Sungji more of a push that he needs for her.