The wording in this does not reflect the love of one adult man for another adult man over the couple’s lifetime. It is a description of pederasty where the older man takes a teenager to be his lover. As we can see in the bit that you quoted, even in Plato’s time there was disagreement about the goodness of such behavior “some have been led to deny the lawfulness of such attachments because they see the impropriety and evil of them.”

Homosexual relations between peers were condemned in Greece and were punishable by death. The dialogues between the players in the Symposium were debates, not law, not the exposition of the norms of the time, just casual discussion interrupted by hiccupping and discussions about how much they had to eat.

Observe that Pausanias says “And in choosing young men to be their companions, they mean to be faithful to them, and pass their whole life in company with them.” this does not mean pass their whole life in a sexual relationship. The sex would end when the teen started growing a beard. The older men would find another sexual partner in a youth, while not abandoning the older one as a friend. The sexual attraction was to their youth. To say that lifelong monogamous homosexual relationships between peers were accepted in Paul’s time (400 some years AFTER Symposium was written) and defend it with this quote is ridiculous. It would be like describing our currently accepted values and norms by quoting Hobbes or Locke.