According to Jim Recap: About a Girl
Dana takes Ruby to the park one afternoon and that just happens to be the afternoon when she runs into a guy. It also happens to be a guy who, himself, is a single parent, and not wanting to blow the opportunity to meet a guy, Dana doesn't mention to him that Ruby isn't exactly her child.
Meanwhile, since Cheryl has a birthday coming up, she asks Jim if he will walk 10,000 steps each day until then. He agrees, then finds out that he's going to be walking something like 40 miles before her birthday actually comes around. Fat chance of that happening.
Lucky for him, Dana needs Ruby, and he brokers a deal - walk the steps and he'll let her take Ruby to the park as if she's his own child. But then Cheryl comes home and wants to take Ruby to her gymnastics class, which raises a completely different issue - those classes cost $25 each, so he scores some money out of Dana for the use of Ruby.
All is well until Dana agrees to let her new beau take her out on Sunday, which also happens to be Mother's Day. Probably not a good idea, since Cheryl just might want her kids around. Jim works out a deal for some extra steps on the pedometer and they figure out how they can make it happen, but then Cheryl gets up early and the whole plan goes out the window.
Dana ends up spilling the beans to the guy and he seems to like her anyway. Who would have thought that would happen?
