I think the big thing here for them might not even necessarily be that he had an affair, but that of all the people he could have chosen to have an affair with, he chose a company employee. In doing so he left them open to a potential lawsuit (plus the scandal and loss of sponsorship/revenue that would follow) and put the entire company in jeopardy, risking the livelihoods of everyone involved. I think if a friend and business partner did that to me, it would tell me all I needed to know about their priorities and where our friendship stood. I would have no desire to stick around for a friend who had so little consideration for how their actions would affect my whole career and source of income.