You asked "What is Easier, to forgive or to trust again?"
This isn't a question that can be answered by just picking one or the other, they both have to be understood.

Trusting someone comes naturally through interaction over time or through reputation.

Forgiveness on the other hand only comes after one has been wrong and is willing to make amends by attempting to restore the relationship.(whether it be between friends, family spouses or neighbors)

Before one can trust again they must forgive to repair w/e relationship was damaged. Next it takes time to repair anything to the "way it was". Even then it's never the same again.

So to go with the flow of things, You have to forgive before you can trust again, Niether is easier then the other but forgiveness comes first.