How to deal with career breaks in CV
I wouldn't bother to explain a break this short on your CV directly. I would instead just have a "canned" response ready when people ask you about it that puts a spin on it to look as good as possible. Something like:

"I wanted to make sure that I stayed in the field that I wanted to be in, and proper opportunities can be hard to come by, and short-lived. I applied for over 90 post-doc positions over that time, but decided that I wanted to make sure that I was open if the right opportunity came along, so I didn't take other work. Instead, I lent extra support to my partner as they started a new position, and made sure that the applications that I put out were top-notch."

Based on your question and comment, none of that is likely dishonest, it's just a nice and clean way to describe what happened in your life during that time. They really just want to make sure you didn't get bored in your field, but seems like you stayed engaged and dedicated to your field, so I wouldn't see it as a problem.