I understand your intentions bro, but what I'm saying is that these words are not effective in helping. Imagine if you were married to a girl as she is, and she becomes a mother. You didn't marry her with children right? But you expect her to care for the child regardless, and if she isn't doing her job as a mother and you get in an argument about it, how would you feel if someone said to her, "It's your husband's fault for marrying you without children to begin with. He shouldn't expect you to do change just because you have kids now." I know it's not exactly the same situation, but you get my point. How would that make you feel as a husband to know this is the advice your wife is getting? it's a different story if this advice was given to the husband himself, but instead it's putting a wedge between them when it's given to the wife since you're putting the blame on him. There's 3 sides to a story: the first, the second, and the truth

. We are only hearing one side, which to me sounds mostly based on emotion. Secondly, they both knew what they were getting into when they got married. She knew she was marrying a Muslim man and he knew he was marrying a Catholic woman. So they accepted the challenges they were going to have in the beginning of the relationship and remained together for 11 years afterwards. I didn't see where she said she's thinking about not being a muslim anymore, but one's faith isn't based on external circumstances. Just because her husband is angry with her doesn't mean she should play around with her faith. You're either muslim by heart and true conviction, or you're not. It's not a game.
Even if he had married a muslim woman to begin with, the exact same thing could happen in that relationship as well. I can't speak for all women, but yes some women are more adaptive than others, some are stronger, some are wiser, but at the end of the day we are each individuals and when you've been with someone for a while, you should have learned enough by that time to understand what works and what doesn't in the relationship. Now in regards to her husband insulting her, it's definitely not something that happened just because she's not fasting. A husband doesn't just start insulting his wife so freely. It's something that began a long time before then and they probably do it back and forth, but she's being sensitive about it now because he's not talking to her.
I'm not saying at all what he's doing is right, I don't know what his issue is or what his side of the story is, so I cannot advise him since he is not reaching out. But looking at the situation from the information she is giving us, and advising her specifically, I can't say that she's doing everything correctly either. Often times also when women are fighting with their husbands, they think the worst of them. And when they are back together, they are totally fine as if nothing happened. So she's sitting here and now thinking how "manipulative" her husband is etc. Ask her again about her husband when she's happy and you'll get a different answer.