Hi again ^^
Obviously there are numerous reasons but I think it trickles down to this. I've said it in the chat but I'll elaborate a bit more here.
In order to go through with suicide, your mind has to be in an extremely dark pitch black place. Now, there's a difference between dealing with suffering on a daily basis/depression and hitting that dark place.
When you're still in the depression mode or suffering, there's still remnants of yourself in your mind. There's still pieces of you in the mortal world.
The only way to get over to the other side is to get to a place so dark that all of you is gone. When this happens, you don't care about yourself, family, friends, lovers, anything that made you happy or sad. When you're gone mentally, you'll be gone physically.
Hope I didn't sound too wacko.