I went on a whole rant about this topic in the comments a couple weeks ago. His family likes her, they had enough money to pay off the debt, she could've given the Count title to Winslet so he'd get something out of it too since he was born the second son, she actually knew Winslet since childhood, her father would've definitely approved of Winslet before he died, and most importantly he RESPECTS HER.
The story is really trying bounce around why she didn't choose literally anyone else. But the excuses make NO SENSE. "Winslet and I are close enough to be siblings" so what your still not actually related and you need an arranged marriage anyway, "my husband was nice to me at the beginning" you still didn't really want to marry him even back then, "I don't want to burden anyone else with my debts" but you were already going to so why not do it somebody YOU KNOW. It really is the worst type of plot hole.
Dude Winslet was right, she should've married him. "Oh, I don't accept kindness blablabla". My gal, even if you didn't love him, you would've a stable relationship with someone that respects you.