Anger, Frustration and ADHD in relationships

I have been just thinking about relationships a lot over the past several year.  

My own parents have been married since 1957.  She was 21 and he was 25 when they married.  My Dad was an active alcoholic till 1991.  Alcoholism was the atmosphere in which I lived till I was 20 and moved into my own apartment.  (I believe he is ADHD -  will never know, he is 84)

My husband's parents, who are both deceased, were married in 1954 (?). She was 27 and he was 40 when they married. Their marriage basically died after their 7th child was born in their 10th year of marriage.  They stayed together because of (they stated) their Catholic beliefs.  That was the atmosphere my spouse lived till we married in 1984.  (He did live out west in Arizona for a few years with his Aunt's family, before I met him.)  (I suspected my spouse was ADHD since our son was diagnosed in 4th grade.  My spouse was diagnosed at the Cleveland clinic in, I believe, 2009.)

I married in 1984 when I was 25 and my spouse was 27.  I spent a lot of time, years actually, trying to figure out why I couldn't get it right.    

My daughter - who is now 24, and my son, - who is now 27, both were in a committed relationship with their significant others since 2009.  My daughter and my son's girlfriend were in the same class in high school.

In January 2013, my daughter got engaged.  (We highly suspect he was ADHD - she really liked a lot of who he was because he was 'just like her Dad.")

My son's girlfriend always said she did not want to get married till she was 30.  When my daughter asked her to be a bridesmaid in her wedding, she was hesitant - what if my son decided to break up with her - - -how awkward would that be?  She was in the wedding.  He did not break up with her.

In Fall of 2013, my daughter got married.  In January 2015, I was 100% shocked when she said she was done.  She wanted a divorce.  And they did. 

My son and his girlfriend dated through her 4 years of college.  And her 2 years of graduate school.  

A few days ago, my son told me he and his girlfriend were "still together"  but she feels she is missing something since they had dated since she got out of high school, so she needs some time and space to gather her thoughts and feelings.  He said he is sad, but alright with it all.  They have a mutual agreement, and he wants to do whatever she needs to be happy.

I am just trying to sit and take it all in. . . . . . . .my head is spinning.  

Diagnosed ADHD.  Suspected ADHD.  Relationships going in with eyes wide open - my son and his significant other. Relationships with undiagnosed ADHD.  

Life is just tough sometimes - - -all the way around.  I feel as though I am just not aware enough of what is going on around me.  How to just let it all be is hard for me.

In a contemplative mood,