he will be wrong assuming what you said
she wont try harder
I'm reminded of an old Abbot and Costello skit:
Costello: When I marry, I'm going to get a plain girl to marry.
Abbot: Why?
Costello: A pretty girl might leave me.
Abbot: A plain girl might leave you.
Costello: Yeah, but who cares?
If she doesn't feel like making an effort, he just moves on.