Breeding for flowers.
I second this. It's been almost a year for me and I still haven't gotten one (granted I had to restart this I think I contaminated the batch lol).To expand upon this, if you haven't earned every hybrid entirely from your own work yet (starting with seed bags and working your way to a blue rose and so on), it is a lot more challenging than you might think and genuinely takes about a month or two of effort, depending on your luck. I began taking the hunt for my own blue roses seriously in May, and didn't successfully breed my first one until early July.
That's kinda what I'm doing.I agree with what a few others have said - the thing that has usually helped me enjoy the game again is to take a break and play another game for a while.