I don't mind answering, and I appreciate you for asking in such a nice way. In all honesty my parents both have mental illness and my dad at least recognized he was out of control and realized he needed help and is now a recovering alcoholic who is at least trying to do ok. In the case of my wedding my dad and I live a few thousand miles apart and he is a disabled veteran in pretty poor health and just couldn't risk a trip during coronavirus but also in good times he doesn't leave his house much. Part of his mental illness is just having a very hard time changing routines so I just told him we'd come visit when we could and he said it's cool :)
My mom is a whole different story. She is someone who has deep deep depression, mood swings and a personality disorder. I also genuinely think she may be on the spectrum because of how hard of a time she has connecting and interacting with others. For example I had a small family party when I graduated college a few years ago and she "went home to feed the dogs" instead of meeting my fiance's family. She came to my house then left then came back later after everyone was gone without meeting anyone. She never even told me where she was going, I had no idea. She has just a very hard time going to things where other people might be or even holding conversations with other people.
She also has a hard time with reality and often gets sucked into these "this person has all the answers" schemes. Her life hasn't been easy but mostly because of her poor decisions and inability to accept and live in reality. Going to her for help or comfort is a mixed bag. She is very very close to my little sister, but in a way where they call each other 15-30 times a day, in constant contact. They even work at the same job. She can be so loving and that's generally how she reaches out: a text with one of those "I love you" bitmoji things or maybe a text that says something like "your sister said you aren't feeling well" because she herself won't check on me. We might go weeks before i get one of those texts. She does the same thing to my older sister. She just doesn't take next steps to follow through. Often I feel that these texts are her way of making sure we are still alive and we aren't mad at her and it sets her mind to rest.
We used to have a very very tumultuous relationship because she was my only parent growing up (dad left when I was 9) and I needed so much that she just couldn't give me. I was very resentful but as I grew older I realized it was either let her be how she is and accept the mom I have or keep beating down the door for something that doesn't exist. I chose peace and now we can spend 30 whole minutes together without fighting. We will never be close though and I have come to accept that but it's still hard some days.