It sounds like your father never got over the loss of your mother. Along with that as he aged he probably felt very lost personally and fearful and ended up self medicating with the alcohol. Perhaps he doesn't really know how to connect and instead has just withdrew into himself. Losing a spouse in mid fifties can be devastating to someone in ways that person doesn't realize but can feel so alone with. It's not like your father expected to experience that loss either, after all your mother was fairly young still. Sometimes a person gets so devasted that they develop a deep fear of "loving" because the pain of the loss is so overwhelming. Also, the helplessness of not being able to do anything about it can actually be traumatic to some people.

Men can struggle even more because they are often brought up to not show their emotions and just "man up" therefore they often don't know WHAT to do with their emotions and it can get so they get increasingly crippled by them and some men do begin to self medicate through alcohol. Emotional pain hurts and can be exhausting, so the alcohol seems to bring "some" relief to that challenge.

I am sorry you are not only experiencing the loss of your mother, but also have seen your father gradually withdraw too. Often this is based on fear and not because he doesn't care about you.