It can be tough holding space for your partner with no formal training. (Heck, even with formal training, it is hard in your personal life!) The best advice I can give you is to seek out services for yourself with a mental health professional, as some of the things that may come up for you may be your own stuff. Dating someone with depression comes with its own share of difficulties, including for the partner without depression.
Plus, seeing you seek treatment will model the behavior for your partner who may have been convinced that only “crazy people” go to therapy. While mental wellness has been at the forefront of conversation this past year due to COVID and pop culture normalizing seeking treatment in rap songs, TV shows, and social media, there is still stigma with caring for and addressing issues in our mental health—especially when it comes to treatment. Your partner may still experience hesitation about seeking treatment such as therapy or medication management. Support them in your words and actions, and they, too, will be the benefactor of autonomous decision-making for one’s overall mental health and wellness.
If it feels appropriate, ask your partner how you can help. Deferring to them allows them to dictate what help and support look like for them, instead of you operating on assumption and possibly overstepping their boundaries. If they are amenable to it, helping them compile a list of mental health providers or support groups is a collaborative way to support your partner in what can be an overwhelming season.