He owns the company and she works for the company. That's a huge conflict of interest, in more than one way.

What if other girls at the company feel like Alex was getting better treatment because she was giving sloppy toppy to the guy in charge? That's a lawsuit.

What if Alex felt obligated to give sloppy toppy to the guy in charge, because he was in charge? That's a lawsuit.

Also, I get that this is a little more morally gray, but engaging in sexual relations while on the clock or on the company dime (work trips, events, etc) is definitely not good for business.

And finally, this doesn't work with the Try Guys brand as a whole. They're known for being "good people." Good people don't engage in long-term affairs with a younger woman while they're wife is at home caring for their sons. They just don't. Sorry.