Sounded to me like he was manipulated. Not that he took any measures to check if he was being lied to.
He said lead was the one thing that was wrong in his otherwise perfect life and the dude said all this stuff in front of a crowd. I don’t think the dude is being manipulated. I’m chapter 1 it seems to me he’s setting the pace just to have an excuse to cancel his engagement through his flamboyant expression and then involving the person that likes him. Personally I don’t like how in general mangas tend to set up cliche fights between rivals and then demonize the characters just because they are opposing peoples otp.
Framing people for something they didn’t do is whack. The guy seems to be controlling the dialogue just because he wanted to end the marriage contract and the girl seems to be quiet following along with him which she shouldn’t if this was real life. But this is a story, who knows what will happen, it’s not my story to decide.