Board Thread:Questions and Answers/@comment-25322628-20170117173017/@comment-1635567-20170120161519

And here's Owen Dennis's (storyboard artist) opinion about this (sources right here):

"I don’t think Margaret is doing nothing, I think she’s living her life. I think people have relationships and they don’t always end up with the first few people they date. That’s actually pretty normal. One of the things that I think people take for granted sometimes is that Regular Show broke new ground in this department when it came to kids television. Before Regular Show and Adventure Time, the idea of going all in on depicting adult relationships in a kids cartoon wasn’t really done. In almost all western kids shows leading up to this point, relationships were generally shown as: boy likes girl > boy gets girl > boy loses girl > boy gets girl back > that girl is their one true love. The end.

This is NOTHING like real life! Relationships sometimes include awkwardness, fighting, arguments, love, and often they just end. Not only do they just end, but they end with very little closure. It fuckin’ sucks and everyone is going to feel it at some point in their life and I think going down the whole “they’ll find their true love the first time” route is straight up disingenuous. Relationships are experimentation and, if you ask any scientist they’ll tell you, experiments almost always fail. To me, personally, it feels more honest and true to life that you would break up with someone, still see them around town, still know their friends, and they’re still sort of your friend.

I don’t know much of anything about Sheri, but I know that she likes art, which is a pretty deep seated thing, just like Mordecai. She also likes him enough to make a couple kids with him and marry the guy. They both seem pretty happy and Mordecai seems a lot more relaxed and at peace with his life. I think if Mordecai were my friend, I’d be happy for them."