Why did he say " mistake of getting married again"?

My female friend, who is kind, funny, good looking, everything nice really, has been dating a guy for about a year (both middle age group). She is a widow he is divorced twice. A friend of his asked them if they would be getting married , he said "god no way, I am not making that mistake again". My friend said she felt like a piece of crap when he said that in front of everyone and upset he was, she felt, lumping her in with his two ex wife's as a horrible woman. He just says he needs space and his own home, so he won't ever live together either even though he loves her. Lots of men would be over the moon to have a wife/partner like her, she is a really decent human being, and he knows it, so why did he show her up like that in a nasty way?

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11 mo
They are not friends with benefits, it is a very committed loving relationship, but in their own homes, one of his exes cheated and one was a horrible person. My friend is a lovely person, and i dont want her hurt.
Why did he say " mistake of getting married again"?
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