My Dad, in his late 40's, cheated on my Mom with a 24 year old co-worker.
My parents separated, my Dad moved in with OW. Shortly after, my Mom was diagnosed with Stage 4 terminal cancer. My Dad moved back home with my mom, my grandmother, and myself.
My Mom passed away several months later, after undergoing rigorous treatment. I was 10, just 2 weeks shy of my 11th birthday. My Dad moved my grandma out within 3 weeks of my Mom's dying, and OW in shortly after.
They married in October of the year my mother died (in mid-July). They got pregnant on their honeymoon. Both became physically & mentally abusive to me. The rest of my childhood was pure Hell.
They remained married & together for about 2 years, then she cheated, ran away, racked up all the credit cards, & hid my little brother from my Dad.
A huge, ugly divorce & custody battle ensued. Luckily, I had a BFF with a stable family & they essentially adopted me for awhile.
It's part of why I got married at 19. I saw my way out. Eventually, my Dad & I came to have a relationship, but I wouldn't call us close. Strained, for sure...but he's in his mid 80's now & I guess I have rugswept everything, so we can have a small semblance of a relationship (over the phone, now, as we're living several states apart after my divorce).
My exWH knew this whole story in great detail, saw how difficult it was for my Dad & I to have a relationship, saw the damage it did... yet he cheated on me multiple times with co-workers anyway. Left our family, discarded his adult kids, burned everything to the ground in the cruelest way possible... and still has zero remorse about it all.
He came from a stable, loving immediate family with a huge, tight knit extended family (I had no extended family- my Dad had lost touch with his, & my Mom was a foster child).
In every scenario you'd think I'd be the cheating risk. Not on your life! I went through that Hell as a kid, I swore I'd never inflict that pain on anyone.
I was misled my my Ex that he felt the same way, too. I guess that's how he felt... until he didn't.
All the FOO has definitely made healing, overcoming, and bouncing back from the betrayal & divorce a lot harder & longer process than I anticipated.