The Kiss bassist - who claims to have slept with over 2,000 women and has for a long time vowed never to marry - popped the question to the actress-and-former-Playboy model, in Belize recently.
In video footage for their reality show 'Gene Simmons Family Jewels', he asks Shannon: "I come with so much baggage, but you're the only friend I've got, you're the only one I've ever loved, you're the only one I love, and the only one I ever will love. I've never said those words to anybody, and I don't ever wanna...
"It's funny, they used to watch movies where they say I can't live without you but for me it's true."
He then gets down on one knee and says "will you marry me," at which point Shannon is crying.
Gene, 61, and Shannon, 54, have been together for 27 years and have two children, Nicholas, 22, and Sophie, 19.
The 'Rock and Roll All Nite' hitmaker has previously made his views on marriage very clear, saying in 2007: "I don't believe man is designed to be married. Marriage means nothing to me. Happiness means everything. All I see in marriage is a lot of desperately unhappy people.
"The problem with marriage is somebody else has a right to say how you lead your life. Not even your mother has that right, and she gave you life itself. Why would you ever give anybody else that right?"