Is there a phrase for the re-establishment of friendship with someone? [closed]

Solution 1:

The term you are looking for is ​to reconcile:

• When two people are reconciled, they become friendly again after they have argued:
  • They were finally reconciled with each other, after not speaking for nearly five years.

Cambridge dictionary

Solution 2:

My father, a WWII veteran, would have called it "burying the hatchet."

To bury the hatchet means:

to forget about arguments and disagreements with someone and to become friends with them again.

[Cambridge Idioms Dictionary, 2nd ed.]

Solution 3:

The phrase you are looking for is "make up"

• to become reconciled (quarreled but later made up) to reconcile with someone; to end a disagreement (with someone).
• to forgive someone and be friendly with them again after an argument or disagreement (from CD)

Bill and Max decided to make up. They made up with each other and are now very good friends.

Solution 4:

A colorful way to put it is to "rekindle the relationship".

Oxford definition for "rekindle":

Revive (something lost or lapsed): ‘he tried to rekindle their friendship’