Heya, I'm a 53 year old man who has been married for almost 30 years and I am in a similar situation as you.
My wife who struggles with PTSD from childhood traumas and who has been self medicating with alcohol has suggested divorce like it's the cure for everything but we are giving it a few months to see if we(she) wishes to work things out .
She also has been showing less affection and warmth for over a year now .
I love her very much still and never wanted to divorce but I'm getting tired of feeling like it's all my fault when I am starting to realize it's not and this leaves me feeling very confused

I also had my father abandon me when I was very young (3) and feel that marriage is something worth fighting for . Our one son is 20 and he also struggles with stuff and I don't want him to suffer and feel the way I felt when my father left .
I struggle with the way this makes me feel so worthless and depressed.
I don't have much advice as I'm still not even sure which way this will work out as it changes daily in terms of her interaction with me . Good days and bad ones .

I just wanted you to know you're not alone in your situation and want to offer you some support for what you're going through if you ever wish to vent feel free to message me .