How do failed parental marriages affect kids?

[kev014]

Fairly straightforward title/question, but slightly further context…

I now have a relatively anxious attachment style in romantic relationships and some fear of abandonment. I recognize that a large part of this is due to my personal attachment/relationship with my mother, but I’m wondering if growing up in an environment without a healthy, secure, loving relationship between my mom and dad has contributed to this.

They never got divorced and are still living together now, but they haven’t been romantic in idk probably over a decade. My dad is kinda butthurt about it and I can tell wishes it was different, but I know my mom is entirely emotionally moved on. I asked if she’d be cool if he started dating someone else and she said yeah it wouldn’t bother her. They are essentially friends/roommates at this point peacefully co-existing. He is kinda clueless and I jokingly say he’s autistic (not entirely a joke). 

I’m not sure how much awareness of this dynamic I had as a kid, but I know it started back in ‘99/2000. 

I have been in therapy for a while addressing my individual relationships with my parents, negative beliefs, processing old emotions/traumas, working through current emotional ‘triggers’ - all the fun stuff. Lot of progress. Wondering though how the relationship dynamic of my parents may have contributed to this.

Does witnessing unhealthy parental relationships harm a child… OR, is more of the issue insecure relationships 1-1 with my parents (I.e. me and my mom, me and my dad)?

Does this stuff create negative self-perceptions/beliefs? Does it create shame? Could I have internalized some degree of responsibility/blame for their ‘failed’ marriage?