updated 07/26/2011 AT 5:00 PM ET
•originally published 07/26/2011 AT 3:35 PM ET
You can’t always believe what you see on reality TV. Case in point: KISS bassist Gene Simmons finally proposed to longtime girlfriend Shannon Tweed.
Turns out, the proposal scene in Tuesday night’s finale of A&E’s reality show Gene Simmons Family Jewels was taped “several months ago,” a source confirmed, and it’s been a rocky road for the pair ever since.
Simmons, 61, and Tweed, 54, were vacationing in Belize when he proclaimed, “you’re the only friend I’ve got. You’re the only one I love … and you’re the only one I ever will love,” before getting down on one knee.
It remains to be seen whether Tweed will be saying “I do” and sticking with it. She did, however, tell PEOPLE in a recent interview that she had moved out of their home and that there was a “slim chance” of them getting back together. “You’re seeing this happy family,” Tweed said, “but in my heart, I am dying.”
The couple, who once described themselves as happily unmarried, have been together for 28 years and have two grown children Nick, 22, and Sophie, 18.
This season of Family Jewels has documented their troubles and family therapy sessions stemming from Simmons’s claim that he has slept with thousands of women. Last month, during a promotional tour, Tweed slammed Simmons for his infidelities and said their relationship had “pretty much unraveled.”
“I need some sort of commitment,” Tweed told PEOPLE, reiterating that their relationship is over if Simmons’s behavior continues. “Something has to give.”
On Monday, Tweed Tweeted that the proposal was “the most shocking moment” of her life.
With reporting by MIA McNIECE