Things are meant to bottom out somewhere. I guess there is no a-priori reason why they should, but things are meant to bottom out somewhere.

Sometimes it is thought to be constitutional excess of agression
Sometimes it is thought to be constitutional structural vulnerability
Sometimes it is thought to be fear of loss of object
Sometimes it is thought to be fear of loss of objects love
Sometimes it is thought to be fear of fragmentation / annihilation

There is meant to be bedrock. When we reach bedrock there our spade is turned and we cannot dig anymore.

What are the defences for?

To guard against bedrock.

Sometimes people talk about some state that is meant to be experienced in infancy. I'm not so sure about that...

But I have a hard time distinguishing between loss of object / loss of objects love / fear of annihilation.

I mean if object goes away you don't experience objects love anymore. To lose an object just is to lose the love of the object. To be left without the objects love... Is to fragment / be annihilated.

He left me. %#@&#!. He %#@&#! left me. I needed him. I don't need him anymore. I don't %#@&#! need anyone. %#@&#! people. I hate them.