I don't watch The Little Couple consistently, but the few times I've tuned in, it seems to me Jen favors Zoe. I am relieved others see it, too. For one thing, for her whole life, Jen is accustomed to being the center of attention, expects to be fussed over, prefers it. She actually is very controlling with Zoe. Listen to her always saying to her things like, do this, sit there. Zoe, being a little girl, complies. To Jen, Zoe is her adorable sidekick, enhancing Jen's stature as perfect parent. Zoe isn't rambunctious enough to steal the spotlight from Jen the way Will does. Jen doesn't want to be upstaged. She wants to make sure there is enough positive footage of her interacting with at least one of her kids so when everything is edited and produced, she gets lots of air time.
She's flustered dealing with an active boy who is the same size as she is. Raising him is more challenging than she realized it would be. She's not sure she likes it. His antics trump the image she likes to craft for herself. She isn't able to mold him the way she does with Zoe.
I just saw part of the episode where they built gingerbread houses. She is working with Will. She has barely any interaction with him at all. She tries to ham it up for the camera. At one point, she is completely gone from the table for awhile with no explanation! Bill, meanwhile, is working easily with Zoe and their gingerbread efforts are more successful than Jen and and Will's. Later, they are taking the Polar Express to see Santa and Jen and Zoe sit in a different seating section with their backs to Bill and Will! Not one big happy or hectic family unit. Jen is all big smiles, able to ignore Will, relax and mold Zoe into the perfect, pleasant plaything.
Bill is the more easy going, natural parent, taking child rearing in stride. Jen seems to be more uptight and doesn't like disorder or when things are not easily controlled. I guess I tire of TLC trying to present perfection when you just know that's not the really how it is.