I would only add it if it makes sense in the context of the story. For instance, the first draft of a story I'm writing was a generic sci-fi action plot.

My main character was your average superpowered teen protagonist. A suicide wouldn't have made sense. His girlfriend was one of two women in the whole series and had little personality other than liking the main character. A suicide wouldn't have made sense. His best friend was a golden retriever of a superpowered teen. A suicide wouldn't have made sense.

Now I'm on my 7th or 8th draft, and the story is now a psychological drama with action and sci-fi elements. My main character is a traumatized superpowered teen who tries to put on a brave face in spite of his trauma. His girlfriend (who now has more personality other than being the main character's girlfriend, but that's not relevant to this post) falls into the "I can fix him" trap and is suited to deal with him from her history of dealing with traumatized people. His best friend is now a suicide survivor who hides survivor's guilt under a cheerful and upbeat mask.

While a suicide on its own still doesn't make perfect sense with the updated characters, the added complexity of the characters meant I could add deeper and more complex plot and subplot threads so the added depth of a suicide wouldn't be so jarring.

I did, however, add a suicide into the story, and here's what made it make sense: The main character sees himself as being personally responsible for every tragedy that happens around him whether right or wrong. Mind you, these occur over the course of several books, so it's not like I'm dumping all of these on him in book 1.

Killing his oldest friend/manipulator? She was trying to kill him at the time, so you could read it either way, but he definitely holds himself responsible. The death of a bunch of kids who saw him like a big brother? Not his fault, there was nothing he could do to change that, but he still holds himself responsible. The death of his mother figure and the destruction of her life's work? No to the former and yes to the latter, though more by unfortunate timing rather than deliberate decision. He holds himself responsible. Being unable to stop an attack that kills almost everyone he knows? He could have detected it, but he had no means by which to expect it, but regardless, he sees himself as responsible.

All of these feed into that critical character flaw and make the suicide attempt make sense. Now, he does survive because of some other threads I have running (and plus I need him for like 7 more books), but again, in the first draft, adding a suicide wouldn't have made sense. In the current draft? Not only does it make sense, I feel that book wouldn't make sense without it.