A similar thing happened to me - my ex moved us as a "family" to Australia, before he unceremoniously ran off with a tart from the office. I looked into moving the children and myself back to the UK, and was told you need to get the fathers permission as part of the Hague convention. Otherwise you can get yourself into serious trouble, and lose your children.
Ireland is not that far to move, so your ex shouldn't have a problem with it. However, without his signature, even if it improves your life, i.e. being near family, it doesn't matter.
In the end I stayed in Australia, as I started to create a great life for myself there, however my ex did in the end return to the UK, and the children and I followed. I thought I'd get lots of help from my family, as they promised, but nothing happened - I was on my own, and had to start again.
As for moving to be near your first love - maybe you should get in contact, and test the water first??