If a teaser for Monday's finale is any indication, that decision won't be without conflict: In the clip, Gibson is shown handing him what Michaels calls her "friendship with mega benefits" ring he gave her a couple years ago, saying, "I told you before that this means nothing."
Later in the clip, the rocker says, "There's something I want to ask you." But, whatever happens, Michaels tells PEOPLE the way it unfolds is very realistic.
"I promise you, there will be no big, fake, phony ending," says Michaels, 47, of what transpires between him and Gibson, 39, with whom he has two daughters, Raine, 10, and Jorja, 5. "It may not be the ending people want to see, but it will be a very real ending."
One possible reason he may not pop the question? Michaels, whose parents split when he was growing up, still has qualms about tying the knot.
"Love and marriage are the ultimate, but I still get a little sweaty about the marriage thing – I don't know why," says Michaels, who's scheduled to have heart surgery in January. "I just hope, should Kristi and I go further, that it doesn't become this thing that in my mind crushes my free spirit."
"I know this sounds crazy," he continues, "and I say it's a mental issue, but I don't want to ruin it by getting engaged. And she hasn't done anything wrong, but I feel like something's not right, and it ruins our relationship."