Entering into a business relationship with an employee bears its own responsibilities; however, all parties know that it's a business relationship. Everyone understands the limits of the responsibilities associated with that relationship & employees always have another employer they can go to if need be.

The same can't be said for a family.

Totally. If you already feel like you're in a space where everything is riding on you, it's not exactly appealing to expand that responsibility. If you felt freer, you may be willing to take on that burden initially.