WHY this double standard exists is anybody's guess and a rabbit hole I'm not about to go down just now. The real relevance in regard to your story is that right off the bat your male MC is going to come off as less sympathetic (moreso I think to female readers than male readers I suspect, make of that what you will) for escaping his marriage than a female protagonist would be for taking the same action. In order to be sure that the audience will accept the MC's actions as reasonable, I suggest that you play up the brattiness of the soon-to-be-wife. Make her not just annoying or childish but unendurable and irritating bordering on evil. Doing that will make sure your MC looks very reasonable in his actions, even to female readers.