I don't think Curly had any decent marriage. I've read both Mow Howard & The Three Stooges and the Scrapbook, and from what I can gather, he was mainly just a womanizer who had a hard time settling down.
I think that might be a bit of an exaggeration, his 'mainly being a womanizer.' I think a lot of that stuff happened in the 40s when he was running around, between marriages. From what I've read in 'Biography of a Superstooge' (which I know well), Elaine, his second wife was very good to him, too; it was the fact Stooges were really picking up popularity at that time ('37-'40) and the Boys were constantly on the road when they weren't at Columbia. That, and Elaine and Curly were just too opposite. She had gone to UCLA, and he never picked up a book. But, according to her interview, she 'never looked at anyone else.'
His fourth wife, Valerie, was the love of his life; they were inseperable. Unfortunately, when he did settle down, he wasn't able to enjoy it for very long. If you own a copy of 'Superstooge' take a look at the pics of him and Val; that was one happy guy. She just looked like she really cared about him.