What to do if you have a troubled relation with your postdoc supervisor? It seems my relation with my postdoc supervisor has hit troubled waters after an amazing start. Things started to turn towards the worse since our first publication together, particularly after I took a parental leave. I'm not sure, if I could do my second paper, as my post-doctoral fellowship is coming to an end by the end of this month.

I'm worried about my career, as his reference would play a big role. Any ideas on how to deal with a bad reference?
(In the time remaining, I hope to fix our relation as much as possible...)
From your comments it sounds like a Setup-to-fail syndrome. https://en.wikipedia.org/wiki/Setting_up_to_fail

The Wiki article is a bit iffy, but it basically means that he somewhat has low expectations of your performance after some incident. Thereby, when something happens he assumes is your fault because he has low expectations nevertheless.

Is usually a toxic relationship because is self fulfilling (you'll end up making mistakes, because he wants to) and self reinforcing (the mistake you just did helps him reinforce the idea that you'll make more).

Is a vicious circle that has to be addressed by both you and your boss (PI, manager, etc). But is usually a good idea to have some other people on your side.

Ultimately, if he is unwilling to change, it is better for you to leave for a less toxic environment.