Insulating our friendships means doing things or taking actions that will protect your friendship from strong, sudden or violent forces like relatives, family, drama, sudden windfalls, ex-girlfriends, unseen circumstances.
It means taking action: you sacrifice, you protect, you defend, you give up things you want, you talk about uncomfortable truths, you affirm people so they know how you feel about them, you reassure them when they are uncertain, you fight for them, you bleed for them, and you forgive them, you learn the things they like…
Because all these actions create an "insulating" layer that make you a friend worth keeping in all circumstances.
They say without doubt and in black and white "you are precious to me and I value our friendship"
….and I don’t think anyone can do more than that.