Not me, but my grandad quickly remarried after my granny's death. He remarried in grief and after he started to come out of his grief, 5 or 6 years later, intimated to me that he regretted remarrying so quickly. He was an honourable man however, so he stayed with her until his death. A shame, because she was a horrible woman.
I think it takes a long time to come out of the shock at being bereaved after a long marriage. The sudden abandonment.
I have a male friend whose wife died from cancer. He got into a relationship very quickly after his wifes death. There was a lot of gossip about it, amongst his wifes friends, but I could see why. He had suffered through his wifes decline and wanted a bit of normality back. It didn't last though. I guess you would call it a kind of bereavement rebound effect. 8 years later, he is in a more stable relationship.