I don't know the details to this story.
But if I were to guess from what I've seen in my life, then the daughter made up or greatly exaggerated some shyt on some "i'll show you" shyt to the boyfriend for doing some shyt she didn't like.
Every time I seen a bytch get her brothers or cousins or father to go beat up a boyfriend they made up or exaggerated shyt cause they wanted to prove a point. Either that or they were crazy as fukk and thought dude cheated cause he didn't answer a call or talked to the wrong bytch or something
That's not to say he didn't deserve it
Who knows what happened. Juss sayin.
Also, unless he was hittin this girl or talkin slick to her, don't think old man shoulda put hands on him. I'm sure if she cheated on him and his mother came and beat her ass he wouldn't be with it. If this bytch is over 18 getting engaged to scumbags she gotta learn that lesson herself. Daddy can't be beating up every dikk head she dates throughout her adult life.
Again though, if he put hands on her or talked like he would then yea, ass beating is called for.