Suicide can be a tough topic to talk about, but it's an extremely serious aspect of mental illness. It's a really hard thing to explain to people who haven't experienced suicidal thoughts. Phrases like "it's a permanent solution to a temporary problem" are profoundly unhelpful. When you are in the dark place where the building is on fire, it does not feel like a temporary problem. Jumping from the building at least has a chance of escaping, whereas continuing to exist in a boring, lonely, meaningless, void is just not worth it.
Hyperbole and a Half explains it well in her comic post Depression Part Two. "It's a strange moment when you realize that you don't want to be alive anymore. If I had feelings, I'm sure I would have felt surprised. I have spent the vast majority of my life actively attempting to survive. Ever since my most distant single-celled ancestor squiggled into existence, there has been an unbroken chain of things that wanted to stick around. Yet there I was, casually wishing that I could stop existing in the same way you'd want to leave an empty room or mute an unbearably repetitive noise. "
No, see, I don't necessarily want to KILL myself... I just want to become dead somehow.
Someone who is having suicidal thoughts may seem fine on the outside, because they are trying very hard to appear normal. They may not want to feel like they are bothering someone with their issues. Here are some signs of suicidal thoughts that you can be aware of so you can reach out to someone who might be struggling.
National Suicide Prevention Lifeline: 1-800-273-8255