Hi Simon and welcome. Well done on looking for help.
I like the heading of this thread « This time I mean it »
The thing is of course you, like I did, have « meant it » many times in the past.
You hae recently got engaged? Congratulations. Does your fiancee know about your gambling? Or that it is a problem?
Has she heard the promises that you mean this time before?
It’s an old saying – actions speak louder tahn words. My family had heard all my promises, came a time they didnt believe any of them. When i started doing things though, getting to GA meetigns, making myself accountable so i couldnt gamble secretly etc well, then they had cause to think « Hey, maybe he means it this time »
The actions that will help you stop gambling are the same actions that might help you rebuild trust etc
What positive actions are you taking?