I'm going to make my boyfriend lose his seat on the train.
What did your boyfriend do to make you want to help him lose his train seat?
He'd been so arrogant to me.
Making your boyfriend lose his train seat is incorrect, even if he has been arrogant towards you. Forgive him and set aside your pettiness.
I'm going to make sure he can't sit down on the train. I'm going to push on him until he falls of the train.
That's a really cruel way to act towards him. Talk about it and work out your differences instead.