I would point out that Momo doesn't seem to be paying rent on the apartment, so it's not like she's a full tenant there. So Marigold telling Dale to get out isn't out of bounds. Imagine if you had a friend or relative living with you rent free and they invited someone over that they knew you were mad at without even telling you. Deliberately to try to get the two of you to talk. I would likely be upset at that myself.
The rights and responsibilities of AnthroPCs seems quite odd, and way in favor of the AIs at this point. We have a very small sample size though. Momo, Pintsize and Winslow all live rent-free with their companions, who provide for all their upkeep and costs, up until the point where Momo got her new chassis. Then she got the job at the library in promise to pay Marigold back. But that was of her own decision to do so. Marigold and other AnthroPC companions seem to be expected to foot the bills for their friends, yet it's been said that the chassis legally belongs to the AI that's inhabiting it. And that they are not cheap for many models. So essentially an AnthroPC is a friend who you are expected to pay everything for, rent, power (food), repairs and upgrades (medical costs), clothing where appropriate... But they don't seem to have any responsibilities other than to hang around with you. It's really more like having a minor that you are a guardian of, but who can leave at any time they wish.
As far as Dale and Marigold go... They very much are having that social awkward/grade school crush going on where they express their feelings by picking on one another, then misinterpreting the signs. Dale and May just had a talk about that on the way over, but we can see Marigold does it too... Like with the hissing scene. After the diner she's feeling all bad and confused about how she feels, so she's going back to the old standard 'blame Dale and lash out at him'.