WMG / A Pink Planet

Steven is a Lonely Rich Kid.

It is established that Steven has free-rein of the Moon Palace, having been raised there by his Family of Choice the various gems stationed there. There has yet to be much of any mention of his social life outside of the Moon Palace gems and his parents, but it is brought up that his vacation in "A World to Change" is the first time he has not been accompanied by an entourage of quartz guards assigned to protect him from any perceived threat, and human presence in the Moon Palace is slim to none. Not only that, but the gems are not allowed to openly talk about him for fear of any of Yellow Diamond or Blue Diamond's moles might discover him.

In "Words on Parenting", Pink's fears of being a bad parent are brought up when Steven learns to say "dada" but has yet to say "mama", a problem that comes about due to not having nearly as much time to be with her son as Greg does managing her colonies. In "A World to Change", when Pink (as Rose) gives Connie a hug, Steven is visibly jealous. While this could be that he wants to hug Connie (who he clearly like likes), it is equally likely that he feels like he does not get that kind of affection from her as often as he likes. This implies that while Pink tries spending time with him, her work as planetary matriarch has cut into their quality time more than he would like.

Yellow Diamond is giving Pink a hard time on her work ethic because she misses her.

In every one of her appearances in A Pink Planet, Yellow does nothing but criticize Pink's different way of managing her colonies, dismissing the attachment she holds over the organic life in her court, calling her application of "psychology" into general living useless and repeatedly bringing up how slow Pink's progress is compared to general standards. There are even implications in "Living and Learning" that Yellow talked White Diamond into changing the standards that she is letting Pink get away with.

From what we've seen in-canon, Yellow would routinely keep Pink out of the way, much like an older sister or working mother trying to keep her baby-sister/daughter away so that she would keep working. When Pink tried abandoning her colony, all she had to say was that she should finish what she started and finish off the Earth. After Pink's "shattering", Yellow was clearly broken (metaphorically) by her little sister's death, blaming herself for what happened, so it was clear that she loved Pink in-spite of having trouble showing it.

Since Pink has her own colony in A Pink Planet and has developed enough independence to experiment without trying to get Yellow an Blue's validation, Yellow has been trying to make Pink's business her own business. Gems are static characters by nature, so it is likely that Yellow's contrarian tendencies are not really born out of an annoyance for Pink's "laziness" or the fact that White is setting different standards for Yellow and Pink, but it is likely that she is struggling to comprehend that her baby sister has grown up and she does not know how to handle it.

God forbid how she'll react when she finds out that not only does Pink have a boyfriend, but a son as well.