Well, I don't think the mistake of his fiancee is enough to make her decide not to pursue the wedding anymore. I would agree if the wedding will be postponed for now but leaving his fiancee totally because of his mistake, I think that's also quite unfair for him. He should not be judged just because he is an addicted gambler, but he should learn to discipline himself instead so he can save the relationship with his future wife.
I can feel the pain with this young lady. But what happened has already happened and she should move on from that. What they should focus more is how to help his fiancee solve his gambling addiction so there will be no problems like this that will occur in the future.
The young lady should understand the feeling of the future husband,her fiancee had made a mistake.So the young lady will stop the because of the small mistake will not be the correct decision.So the young lady should make her future husband to quit the gambling addiction and the she can marry her fiancee.But quit of gambling addiction is very hard one,but the gambler can do the reduction from the gambling addiction.The gambler itself understand the mistake made by him and ask apology from her lady. Asking apology to her lady is not the wrong one,he should agreed the mistake of miss use of the funds at the marriage time.If the lady not forgive her fiancee, then the gambler may commit suicide because of this loss.