My feeling is that none of the cost of your fiancée's own wedding is a valid business expense. I'm sure that having the business pay the cost of your own wedding is not "common and accepted in your field of business." Her wedding is a personal expense that she would incur even if she were not in the wedding planning business. If her purpose for getting married is to produce marketing material for her business, you should probably rethink the relationship.
For the travel and meals in particular, IRC Section 162(a)(2) says you can deduct travel expenses "while away from home in the pursuit of a trade or business." But she is not away from home in the pursuit of a trade or business. She is away from home to arrange her own wedding. And if any of the travel expenses are for you, they are certainly not business expenses.
