Bf (34 M) taking antidepressants, I (32 F) need advice on navigating this and not damaging our relationship

Me (32 F), and my bf (34 M) have been going out for more than 6 years and living together for a large majority of that. Our routines and habits have been the same for years at this point.

Recently, my bf started taking antidepressants, I'm really proud of him for taking the steps to help support his state of mind and better himself (something I encouraged him to get the ball rolling on). However, since he's started taking them, our habits, routines and behaviours have started to shift, from a very affectionate relationship, to less so.

I'm finding I'm starting to spiral, I'm getting upset frequently and my anxiety has gotten quite bad at times. I feel like everything is changing and it's unnerving me and making me feel quite off balance.

I'm not sure how to resolve this or improve the situation. I don't want to make my bf feel bad, or make him feel like he shouldn't be taking them, I want to support him better, but I want my stress around it all to also reduce. Not sure if there is a happy medium or if I just 'suck it up' in the meantime.

How is best for me to navigate this situation without damaging my relationship? (bf is very sensitive around this topic), any advice or experiences shared would be greatly appreciated. The medication is mirtazapine, if that helps.

TLDR: bf started taking antidepressants, the changes in routines and behaviours are throwing me and I need advice to navigate this.