Yeah Vito was p*ssed with Sonny about it, I certainly think he disapproved. He felt that it was clouding Sonny's judgement 'I think your brain is going soft,' etc etc and also there's the telling moment when Sonny comes into the office after banging Lucy and Vito glances at him, then says to Johnny: "You spend time with your family? Good. Because a man who doesn't spend time with his family can never be a real man". This is directed at Sonny - I don't think Vito was best pleased that he had to send Tom searching for him at Connie's wedding, or that he turned up late in the office when Tom had managed to be there all day.