In my day job, we have a project to replace an IT system. We have the opportunity to take all the good parts from the old one and fix the bad bits. We can do this in life too.
Physically moving to a different climate, moving to a different partner, moving to a different job. But the new thing will also have other bad bits that you were not aware of at the time.
In our IT system example, we have managed to fix some of the annoyances of the past but things that we thought were going to be amazing have fallen short of the sales pitch and now have become annoyances themselves. Some of them are because the new system is worse than the old one in some areas and one because although it has gotten better, the benchmarks of expectation have moved on.
The same is true of our other examples. Moving to a different country? Now you complain it is too hot rather than too cold. Moving to a different partner? Now you complain they smother you with too much attention rather than being too aloof. Moving to a different job? Now you complain about the hours required rather than the salary.
There is a way, however, of taking all the good parts of life and leaving the bad bits. You just need to cultivate two habits: gratitude and not complaining. Realise that the only thing in your control is your mind, then you may take a second through before taking physical action.
Gratitude and not complaining sound like the same thing, but in practice, they are subtly different. Gratitude is being grateful for what you already have in the past and in the present. Not complaining is the ability to catch yourself in the moment. Gratitude is a proactive practice. Not complaining is reactive practice - the last defence - but still in your control.