I would like to think a marriage with Peter Townsend would have worked out for Margaret, but her personality may have been the downfall. The only thing is if she was so in love with Peter, he could have "tamed" that personality. We'll never know will we?
I've read that when Peter remarried, Margaret was heartbroken and devastated. That was when she turned on the attention to Tony Armstrong-Jones. Don't know if it's true.