ML isn't my fave, but Mildred looks so young and she talks about her husband so little it's hard to remember her husband hasn't been announced dead. I'm assuming ML knows her husband is dead, so that's why he keeps slipping. This guy seems like one of those types that looks like a playboy but doesn't actually have all that much experience courting, so he keeps putting his foot in his mouth since he's so thirsty for Mildred. Doesn't make him likeable, but frankly for the time period it's more realistic if he's at least a little narcissistic and controlling (esp since he seems to be an only child), and Mildred can train it out of him.
@chuchuchoerry Her brother is married lol, I think that's the woman trailing after him. He's just trying to use Mildred to get additional security. To some extent he may be worried about her financial situation (they are not doing very well atm, and she has 3 children to support) but it also looks better for his family's lineage if he can talk about a sister who is married to someone successful.