To him, it didn't matter if Kate said that Henry shouldn't even bother doing anything against Erin because she wasn't his problem.
He knew it was her problem, but that problem made him restless. It made him unable to focus on his job or plan because he kept thinking about how Erin could bully Kate and make her cry again in the future.
So, he should still do something against Erin. He just had to find an ingenious way to get rid of her without simply killing and ditching her so that Kate wouldn't notice that Erin's demise was his doing.
"Maybe the problem was Erin all along," Henry guessed. "Maybe I should get rid of her first, so Kate can stop shedding her goddamn tears that could make me so restless."
"Once things have been settled with Erin, I should be able to make Kate fall madly in love with me, so she would do everything I tell her later."
