It's not super hidden that "Crazy Ex-Girlfriend" is looking at the long term effects of trying to live your life like you're in a rom-com. Rom-coms operate on the assumption that no matter what the character says at the start, things are always better as a couple. So provide no guidance on planning a life for yourself. (And in fact often suggest that plans you make for yourself will be upset by your impending coupledom.)
Heather, who seems super together, was still living with her parents. Hector is living with his mom and seems exceedingly happy with this arrangement. Valencia no longer enjoyed being a yoga instructor, but didn't know what else she should be. Paula had always wanted to be a lawyer, and then, when that got in the way of supporting her husband' Scott, her worst fear came true. He cheated on her and validated all her worries that going after things for yourself make you unlovable.
So if rom coms have taught us bad behavior in the name of love gets rewarded, we have also been trained by media that coupling up is the desired way to approach life. Even TV shows that tend to shy away from permanently coupling anyone at the center of a show usually break that rule for the series finale, because we view weddings as closure.
[PS. If you're still reading and haven't watched the season finale yet - spoilers ahead.]
The first season ended with a wedding, and Rebecca finally getting the dream of getting together with Josh. (Never mind that at the beginning of the day her dream was getting together with Greg.) The second season ended with her wedding day to Josh, with Josh, being the one to realize that this wasn't right. Possibly because having the lighter load on planning, gave him more time for introspection.
It is both silly and true to look to hard at the metaphor the show presented of Rebecca's wedding planning. Rebecca decided to plan this wedding on a certain date because it being available was a sign even though she had no idea how to plan a wedding. She found a picture of a pretty wedding and tried to recreate that exactly regardless of if it had any meaning for her or Josh. But, when she let her friends help, Valencia showed up with a perfect plan. Nathaniel got Rebecca's dad there. And Paula yelled at Rebecca's mom until she fell in line. And Father Brah told Josh he dealt with uncertainty by attaching himself to the first pretty girl he could find.
So yes, Rebecca's dad turned out to be a jerk. Rebecca's mom showed that underneath it all she cared for Rebecca when she tried to steer Josh away from talking about Robert. Trent tried to spoil Rebecca's wedding but ultimately it wasn't Rebecca's past, but Josh's own uncertainty with his life's direction that had him choosing priesthood. So Rebecca tried to create a perfect picture of a wedding, but what she got was a group of friends who stood on a cliff with her ready to give her whatever she needed.
I can't wait to see what happens next.