As you've presented it, your wife's airfare is not an allowable expense of your business.
As a business owner, you are not just an employee & you are likely to be audited at some point. If you have detailed legitimate records, the IRS will likely stay on point, & the audit becomes a formality. Give them reason to start disallowing your "expenses" & their audit can easily turn into a fishing trip, plus you will own interest & penalty on the disallowed items. Not worth it, IMO.
How your business is filing can determine your chances of an audit; Schedule C expenses are audited much more than a Subchapter S return.