My mother remarried later in life. She met my stepfather at a widow and widowers club and they were together for about 30 years before she died. He recently married again at the age of 92. He was younger than my mother, but his new wife is younger than him, at 70. She's younger than me! They met through church, I believe.

That's the key I think - meeting in person, through social clubs and activities or hobbies.