After 28 years together, legendary KISS bassist and former Playboy Playmate of the Year Shannon Tweed are finally tying the knot.  On next Tuesday night's season finale of the couple's reality TV show "Gene Simmons' Family Jewels," the 61 year-old iconic rocker proposed to his longtime girlfriend and the mother of his two children.  Fans of the show will have to wait until Tuesday to see if Tweed accepted the proposal, but the fact that Simmons popped the question is a definite change of heart for the bassist, who has always been critical of the institution of marriage.  "Marriage means nothing to me. Happiness means everything," he once said. "All I see in marriage is a lot of desperately unhappy people."