Dear 0reviana,
The decision largely depends on the situation with your current mate. Such a commitment should not be given up lightly, else why does the choice matter?
If your already-mate wants you and is not mean to you, but you choose the new one, how can any mate ever trust that you will not decide to dump them in the future for someone else?
If your already-mate has no objections to your moving on, then why stay?
If your already-mate wants you but is very mean to you, get yourself and any hatchlings you have out of the nasty situation as quickly as you can. If the new one shows signs of being abusive too, stay away from them too.
Best wishes for happy relationships,
Awdz
P.S. My answer would have been very different if Rachival had never been invaded and I were not Gifted. Traditional arranged gnome marriages were never to be compromised, and side-tinkering love was forbidden.