Well... no surprise.
I still don't blame her, she was too emphatic during most of their interaction about being better for both of them to end e their "relationship" quickly.
She could be manipulating him so that he insists, but some of her reactions were... too sincere.
Even if she looks human, and can act the part, is pretty clear her race doesn't work the same way as ours.
I even think she let him go when she tried to eat him, with how by surprise she caught him, she could easily have killed him if she wanted, so left her instinct to take over a little to scare him so that he would learn his lesson... not going according to plan if it is that XD.
Mikane's dad is doing hi best, he is a good dad.