Meg first approaches Sam, only to be rebuffed because of the guilt he's suffering over a daughter he hardly sees. Then Meg tries Nick, but learns he's not physically capable of helping her.
Meg shares her decision and strategy with Sarah as they make apple pies in the kitchen while the football game is occupying everyone else's attention. Who's left? Michael and Harold. (Sarah adds, "Too bad Richard left," a dig at Karen's boring but stable husband.) As Meg ponders the thought of "a repeat performance" with Michael, who volunteered during the first quarter of the football game, she concludes, "I can't do it with Michael. Too much history," and tells Sarah she's just going to have to forget about it this weekend; "it just isn't going to happen." Sarah asks, "Harold's not good enough for you?" Meg: "Are you kidding? I'd love it. But Harold already has enough kids. Besides, I couldn't ask that of you." At that moment we can almost hear Sarah's wheels turning.
Later that evening Sarah approaches her wonderful husband and -- after ascertaining that he loves her -- she sweetly says, "Harold, I want you to do something for me." There's 'a certain symmetry' to this scene. Earlier we learn that Sarah and the late Alex Marshall had an affair while she was married to Harold, and Harold found out. Maybe giving Harold permission to sleep with Meg would reduce Sarah's guilt for having slept with Alex.
Two quick scenes later, "in the midnight hour," Harold knocks on the door of his own bedroom where Meg is quartered for the weekend, announcing,"This bed has always been lucky for Sarah and me." The rest, as they say, is (film) history. (But we never find out if that bed was lucky for Meg. No sequel!)
As Harold and Meg, Karen and Sam, and Nick and Chloe are all "otherwise occupied," Michael tries unsuccessfully to seduce Sarah before the rolling camera, cooing, "Sarah! I never noticed what beautiful feet you have." (There's a line guaranteed NOT to sweep any woman off her beautiful feet!) He adds, "I'm picking up a vibration; I'm almost certain there's sex going on in this house." Michael may be a lot of things, but stupid isn't one of them. He knows he lost the "Make Meg a Mommy" contest, struck out with Chloe, and watched Karen go after Sam.
The next morning, Michael greets everyone in the kitchen asking, "How'd everybody sleep last night? DID anybody sleep last night? I did. All alone in my little airplane...")