depends on how you feel about your life
I'm guessing that you're talking about suicide.
It's frightening because you know what it can do to your family after it happens, you know how destroyed all your loved ones would be, even if they knew about it. You do not want to leave them but it seems like the only way.
The relief part comes in because not thinking about the ones you love ( and who love you ) for a minute or two, it's something that YOU want. You want this for yourself, which is why it's a selfish decision. You want to end things because you think that it'll set you free when chances are, it probably won't. Imagine everything that was once said about heaven to be completely fake. There is no afterlife or reincarnation. You are just dead. That is it.
I always thought of it - life mixed with suicide - to be like a bad marriage. You are in a relationship with life. You find out that you no longer love life, therefore you want a " divorce". You want to leave, you hate it, you want to be happy "somewhere else" but you stay and try to make it work for the ones that you love.
I suffer from depression. Sometimes death would get its grip on me and I would think what a relief it will be for all this to go away and life to just end.
Then I lost my brother to suicide and realized that death is not the easy answer, it leaves behind a lot of pain and hurt.
Taking your life is something you need to get help with. I am here if you need to talk.
I think that the frightening feelings come into play because for some people there is the unknown. What's going to happen when I die. Will I never exist again. Is this it!.... And the feelings of relief come when people feel hopeless.
On the times when times it seems like it will be a relief? Maybe a Saturday morning .....after a very late Friday partying?