Everything that happened is his fault, if he had told her the night he had the chance maybe she wouldn't react the way he did. What Kendrick has said might be different from what he wanted to let her know. Everyone had their secrets, probably those deep secrets that should remain within your heart.
Staying without his Hazel is not an easy task, she should call like five times now, he just wanted to hear her worried voice from the other end, her caring for him and reciting I love you a couple of times. He was losing it, he was going crazy just at the thought of living without her. He knew how torturous it has always been for him when he travels to different countries for business meetings, but the thought of seeing his happy family has kept him going.
But just as she's said, they're better off alone. He can't be with someone ready to break their marriage cause of other people's words about him, a man she's asked to stay away from.