I agree, not logical---yet it apparently happens a lot. The explanation I hear is that they are "safe," and that they make no demands on the women, who are at a "lull" in their relationship with men. They make good dance partners, and have good fashion sense, too :)
It brings to mind the Burt Reynolds, Dinah Shore, relationship of 20 years ago or so. Burt has said Dinah was great and he loved her very much and was experiencing terrible loss when she died. His book which I have not read tells all.
Burt in his day was top box office for eight straight years or was it 12 straight years. He lamented he wasn't mature enough to not let Sally Field get away. They were very much in love ... "Smokey and the Bandit" days.