4. Caitlin Snow and "Jay Garrick" (a.k.a. Hunter Zolomon)
Caitlin Snow has really been unlucky in love throughout The Flash's whole run. As we said earlier, a huge problem with the character early on was the fact that the writers continually wrote her into traumatic relationship after traumatic relationship and that really came to the forefront when she was paired off with the villain of the second season, Zoom.
Even though things started well for the pair, "Jay Garrick" showed up not long after the death of Caitlin's husband Ronnie Raymond, so fans just weren't thrilled about the idea of the writers jumping over her grief so that she could be quickly stuck into another relationship. The reveal that Jay was actually Hunter Zolomon in disguise really frustrated those further because it's not what the character needed after all of the suffering she went through early on in the season (and in season 1 for that matter).
What should have been a meaningful and powerful moment in Caitlin's journey towards getting her life back was simply just a convenient means of furthering the story. Caitlin and Jay's relationship was simply set up to make the Zoom reveal all the more shocking. And sure, mission accomplished, but Caitlin deserved better than this.