Did Cosmo and Wanda have a fairy Timmy back in the day? I hadn't watched A New Wish yet but iirc their relationship was strained by Timmy, I think because of the whole "no one aged for 50 years" thing in Timmy's Secret Wish. So would that mean Timmy messed up their marriage?
Yep! Timmy was Cosmo and Wanda's first fairy!
Cosmo and Wanda were newly weds with no support systems thus miserable enough to get their own fairy!
For the first few years, the three of them were perfect but Timmy overstayed his welcome, none of them wanting to lose this new family they created. Timmy used his magic to try and force a magic solution to make Cosmo and Wanda happy again, to varying levels of success.
New fairy management notices that Cosmo and Wanda seem to be getting more miserable despite having Timmy, so they get assigned a new fairy:
Chloe is here to fix all of Timmy's mistakes. But their happy little family isn't going to be separated so instead of being replaced, Timmy and Chloe end up as coworkers.
But even with two fairies, Cosmo and Wanda keep getting more miserable. With a fresh new set of eyes and someone to talk to, Timmy finally admits that the Fairywinkle-Cosmas might be better off without him since most of their conflict does seem to revolve around magic. So both Chloe and Timmy resign, erasing Cosmo's, Wanda's, Poof's Peri's and Sparky's memories of magic.
That day, the Fairywinkle-Cosma's pet goldfish, the one they got when they got their first house, dies. The whole family is very torn up about it, crying even though they don't know why they feel so strongly about losing this goldfish.
As for the whole 50 year time loop thing:
After granting that accidental wish, Timmy does not come clean about it for 50 years in fear of getting into trouble. A swap version of Timmy's Secret Wish does happen and undoes the time loop but yep, that wish absolutely contributed in the decline of their marriage. Not that Cosmo and Wanda would remember it anyways
