Not saying it was due to family arguing, I'm just pointing out that there are other troubles besides the state of his Dad. When you've got a parent as close to death as Philip is (and I mean due to his age and general decline, not that death is necessarily imminent) it can take very little to push you over the edge. When my mother was terminally ill in hospital I left the ward in tears more than once because she'd been so nasty to me. People do take their frustration and anger out on those close to them.
The mask hides a lot, but at the same time focuses attention on the eyes, so he may have mistakenly thought his emotions were hidden.