It is odd that God never stops these horrible acts. Especialy the ones where the one being harmed isn't the one fucking up. The daughter is killed when she did nothing wrong.
The whole book of Judges is essentially "Here's what not to do".
Pretty messed up that the only way to teach this lesson is to kill an innocent girl and set her on fire. You would think an all powerful being was more capable than that.
Not once did God command him to offer up his daughter. He decided to try and work for God's support, and to try and earn it. But it bit him back harshly.
Here is where the BS comes in. Throughout the book God stops people from doing things. He kills people who sin, makes them fall out of favor with their tribe, stops their actions. None of that happens here. God helps win the battle knowing an innocent girl will be murdered that serves no purpose and God is complacent.
Pull out early instead of impregnating your sister in law, God kills you. Make fun of a bald guy, God kills you. Turn around to look at your home being destroyed, God kills you. I guess having a warmongering father is worth your life too. There just wasn't anything God could do.