εἰ δ' ὃ μὲν διαμένοι ὃ δ' ἐπιεικέστερος γίνοιτο καὶ πολὺ διαλλάττοι τῇ ἀρετῇ, ἆρα χρηστέον φίλῳ; ἢ οὐκ ἐνδέχεται; ἐν μεγάλῃ δὲ διαστάσει μάλιστα δῆλον γίνεται, οἷον ἐν ταῖς παιδικαῖς φιλίαις· εἰ γὰρ ὃ μὲν διαμένοι τὴν διάνοιαν παῖς ὃ δ' ἀνὴρ εἴη οἷος κράτιστος, πῶς ἂν εἶεν φίλοι μήτ' ἀρεσκόμενοι τοῖς αὐτοῖς μήτε χαίροντες καὶ λυπούμενοι; οὐδὲ γὰρ περὶ ἀλλήλους ταῦθ' ὑπάρξει αὐτοῖς, ἄνευ δὲ τούτων οὐκ ἦν φίλους εἶναι· συμβιοῦν γὰρ οὐχ οἷόν τε. εἴρηται δὲ περὶ τούτων.
But if one friend remained the same while the other became better and far outstripped him in virtue, should the latter treat the former as a friend? Surely he cannot. When the interval is great this becomes most plain, e.g. in the case of childish friendships; if one friend remained a child in intellect while the other became a fully developed man, how could they be friends when they neither approved of the same things nor delighted in and were pained by the same things? For not even with regard to each other will their tastes agree, and without this (as we saw) they cannot be friends; for they cannot live together. But we have discussed these matters. (Trans. W. D. Ross)
NE 9.3 1165b23–31
Anyway, it reminded me of this: Julie Walters being brilliant in a brilliant film. Because moving apart can be painful on both sides. Both people lose something, whatever else one of them may have gained.