One founder was removed from the "Founder's Suite," because it was believed that having a woman as a founder would work against the company's valuation/brand-equity. That is black and white sexual harassment. It is discrimination based on gender. Period.
Secondly: Founders date. Employees date. Subordinates and Managers, date. It happens. It's not "should they," it's that "they do" and there are appropriate methods to mitigate this. What is personal, is personal—and what is professional, is professional.
HR departments have methods to mitigate this. Startups being "above" or "too cool" to engage HR professionals early in their lifecycles, are to blame for most of these kinds of problems. GitHub, now Tinder, and many others I can't think of off the top of my head. HR exists to keep the personal, personal—and the professional, professional.
There is NO blame for a relationship going sour, at the professional level. None. Our industry has a ways to go. We all need to be in on that, together.