Yet total honesty is highly unpractical...

That is not the same thing. I studied a lot of interpersonal communication books (why I am so articulate before you ask) so that I could always speak to the woman I loved without adding extra contextual baggage that I did not want or mean, and that sort of communication ability is important in being able to be honest with someone else without needing to cover up one's intentions out of fear of being misunderstood or reviled, and it also takes courage not to lie, if you are without these things (unless you are hiding something silly like a surprise party) the problem becomes much more complex. I thought of the pact between the suitors of Helen of Troy written by Odysseus and Menelaus before the Trojan War as the best compromise between those seeking a life with the same person, as I still do today.