The chances that he and his on-and-off girlfriend of 16 years will decide to marry are now about "50/50," the rocker told PEOPLE on Monday in Vegas. That's way up from the past few years – his VH1 Rock of Love days – when the odds were probably 1 in 100, he says.
"We've been talking a lot about getting engaged, and we'll see what happens," said Michaels, 47, who was in Sin City to co-host the 2010 Miss Universe Pageant. "We just want to make sure we're not doing it for anyone other than ourselves."
Michaels says he and Gibson, 39 – the mother of his two daughters, Raine, 10, and Jorja, 5 – grew closer than ever during his difficult recovery from a life-threatening brain hemorrhage this spring.
"Fate has a strange way of intervening in your life, and I think everything just kind of came together," he says. "Hopefully we'll get engaged. But if we don't, we'll still love and respect each other."