We looked at this a little last season too, when Heather went to visit Greg's mom's family and discovered they were super nice. This season Rebecca brought Josh home for a family bar mitvah, and hoped that having Josh there would help her stay on a cool California wavelength. One of my friends said that when she brought her now spouse home to meet her family for the first time, afterwords, her spouse said, wow, you had warned me, but they are quite something. And I think we all kind of want that. We all feel misunderstood by our family. (Okay fine, you raising your hand there, have no troubles, so fine, almost all). Having someone come home and take our side is an amazing thing.
Yes, Heather set Greg straight. And Josh was right, that Rebecca wanted to see the worst and the unhappiness, but in his delightful and charming ability to see the best in just about everything, he also couldn't see how her mother's behavior affected Rebecca. He couldn't see that Rebecca wasn't wrong that her cousin was digging at her unmarried status, and that underneath at least some of the questions about her move to California, were concerns that what she had done was so ridiculous that it must be a sign of mental illness that she should get over.
Now of course, Rebecca does have some issues that need to be addressed. And certainly, from her family's perspective, where they have likely only gotten her mother's side of this decision to go to California it doesn't make sense. Much of the world does not really value, my job was making me unhappy even though I was succeeding and making lots of money, so I quit, and moved across the country to live in a lower stress environment, and because Rebecca doesn't fully understand that that's really what she did, she likely hasn't explained it well.
But, family also does cause you to regress. And so Josh in trying to smooth things over for her, smoothed so well, and had so much fun, that Rebecca didn't get to live out her dream of sitting in a corner and bitching about everyone, which likely also isn't a healthy choice. But it is understandable.