Temporary.

Everything in life is temporary.
Family
Friends
Love
Pets
Life itself.

But it's what happens during then that makes living worthwhile.

When you have good memories hanging out with friends, that's what makes life worth living
When you come home and the most amazing animal comes running to come greet you because to them, you are their world. That's what makes life worth living.
When you are wrapped in the embrace of a lover or friend after having a hard time, that's what makes life worth living.

But…

What if none of that happens?

What if, all your friends leave? Break your trust? You can only lament on the past instead of look on into the future, stuck in the past.  that's what makes life not worth living
When you come home to either the silence of an empty abode, or yelling and screaming for something you did wrong, that's what makes life not worth living.
When you have a bad time, but there is no one to embrace you, and to tell you that everything is going to be fine.

When no one is there to tell you it's going to be okay
When no one is there to tell you that there is going to be a tomorrow
When on one is there to tell you

“Don't do it”

That's what makes life not worth living.