Does it mean "it is best to leave old friendships alone"? I've never learned this kind of structure. Is it the superlative form of like "She better be left alone"?

32)Old friendships that have gone *dormant are best left alone. Sometimes, meeting an old friend after long absence can be terribly ① disappointing2. So far apart might friends have grown, or so ② differently2 might they now view the world and therefore each other. One is left to wonder, “God, what did we ever, in those distant days, find ③ attractive2 in each other to begin with?” This becomes all the more ④ enjoyable2 when one party to the old friendship feels the friendship