When he learns that his partner has a borderline personality disorder a depressed guy uses unconventional methods to fix a relationship disrupted by a cloud of mental illness.

Could be interesting, but needs more clarity.

Actually border line personality disorder (BPS) is a specific and clinically recognized disorder. But not one likely to be familiar to many people who read the logline. Which means it is likely that many people won't grasp the character flaw /relationship problem of the story.

I concur with Nir Shelter that the logline doesn't state a specific goal. "Unconventional methods to fix a relationship" is vague.

My sense of the logline is that the MC' with one mental health problem --depression -- assays to treat a character with a another mental health problem. But I have no sense of what the actual plot is. What is the MC's specific objective goal? What's at stake? What does he stand to gain if he succeeds, lose if he fails? Who/what opposes his effort?

And what about his own depression? Isn't that also a stake issue? (Although, realistically, treating the other character's problems won't alleviate his depression.)

Actually border line personality disorder (BPS) is a specific and clinically recognized disorder. But not one likely to be familiar to many people who read the logline. Which means it is likely that many people won't grasp the character flaw /relationship problem of the story.

I concur with Nir Shelter that the logline doesn't state a specific goal. "Unconventional methods to fix a relationship" is vague.

My sense of the logline is that the MC' with one mental health problem --depression -- assays to treat a character with a another mental health problem. But I have no sense of what the actual plot is. What is the MC's specific objective goal? What's at stake? What does he stand to gain if he succeeds, lose if he fails? Who/what opposes his effort?

And what about his own depression? Isn't that also a stake issue? (Although, realistically, treating the other character's problems won't alleviate his depression.)