"Nobody saw it coming, but before we knew it he was gone."
Therein lies the problem. Parents who hide their disagreements and frustrations with each other from their children generally feel it's the right thing to do.
However when a breakup/divorce occurs it's the equivalent of pulling the rug out from under what the children thought was a stable family. Had you known how unhappy they were as a couple you wouldn't have been "shocked".
Unfortunately there are some men who dislike their exes so much that they don't want to have to deal with them in anyway which causes them to turn their back on "her children".
Essentially that's (their perception). It's not about you but rather about (her). They don't want any reminders of her.
You said: "He is in a toxic relationship, and he doesn't belong with her..." And yet (he) isn't leaving (her)!
(No one is "stuck" with anyone. He's proven that!)
One thing that is certain about life is it's unpredictable.
You may end up having a relationship with father several years from now. There's a couple of things you should keep in mind.
A divorce is a public admission that a mistake was made in the mate selection process. One or both people felt their life would be better without the other in it. Human beings make mistakes!
Generally speaking there are 3 basic reasons why couples get divorced.
1. They chose the wrong mate. (Discovered they're incompatible in too many areas.)
2. Someone committed a "deal breaker" in the eyes of the other. (cheating/abuse..etc)
3. They fell out of love over time. (We're either "growing together" or "growing apart")
Note: None of the above have anything to do with the children.
The biggest mistake your parents made was giving you the illusion that they were happy. As I stated it's no wonder you would develop "trust issues". Therefore you "question" whether things are as they "appear to be" in your own relationships.
This can also be the cause of having "abandonment issues" which can lead to pushing someone away before they have a chance to "disappoint you". The reality is we all have our own "baggage".
Some people have the courage to "work on themselves" while others do not.
When we change our circumstances change.
Life is a (personal) journey! Don't let your parent's divorce ruin (your) life.