Your Partner Isn’t Your Therapist
She can love you and still not be equipped to treat your depression. Those are different jobs.
Expecting your partner to be your sole emotional support is unfair to her and ineffective for you. She's carrying the relationship, the household, her own stuff, and now she's also supposed to be your therapist, your cheerleader, and your coping mechanism. That's not a partnership. That's a one-person support team running on fumes.
Get a therapist. Get on medication if you need it. Build a support network that isn't just one person. Your relationship will actually improve when you stop using it as your only mental health resource.
She's your partner, not your treatment plan. Love her enough to get help from someone whose literal job it is.