I know this is late to the party but I wanted to address this. I think it actually made a lot of sense. Twisted sense but sense none the less. He knew he was falling for her and it sounds like he couldn't resist going to see her and it would jeopardize the expansion. He planted the tumor in her head, a sort of burning your bridges behind you scenario so he knew he couldn't go back to her and he would complete his work. It's evil but it makes sense.
This.
Ego can genuinely love her and still do that. It's not an/or situation.