What happens to turn marriages sour?

[newcurtainsNo9]

I read so many threads on here from women with men who sound awful. Hateful, spiteful, vindictive, mean and unkind. At some point, these couples were (presumably) in love and wanted to be together forever.

I'm single after 20 years with my childhood sweetheart, and I'm wary of meeting someone new in the future. Why does this seem to happen (I know not often, or usually but it does happen).

I'm not talking about classic abuse, I know about abusers and controlling behaviour and how it can evolve and manifest. I'm talking about clearly very unhappy marriages. Why does the love go? Is it when the attraction goes?

Not pulling his weight at all once kids came along was a bit thing for me. Lost any love for or attraction to someone who after so long because utterly selfish to the core, and clearly didn’t love me if he thought that was ok.

My husband is a nice enough man. There were red flags and I didn’t see them. He was always lazy and took me for granted. It was just that I said it “didn’t matter” or made an excuse for him. He is loyal, faithful, absent mindedly kind and not at all abusive. However his inability to put himself out in any way to help or support me and his failure to ever think of he first just ground me down. After 14 years of marriage I couldn’t make excuses for him anymore, I couldn’t buy my own Xmas present again, I couldn’t pretend anymore that he was able to love me and care for me and look after me like I did for him so I left him.