The "know" here is not speaking of mere head-knowledge or intellectual ascent ; in fact, it is a different word in the greek ('epignosimai' rather than 'ginosko') - here, Paul is speaking of "know" in the most intimate of context (much like Adam "knew" Eve - Genesis 4:1). So the literal translation would actually read more, "...we will love intimately as we have fully been loved intimately". When understood in context, it sheds much needed light on this passage; everything that we do now, including love, is done "in part" (incomplete). It is this way until the maturation process is completed in the return of Christ. At that point, all other things, save love (1 Corinthians 13:8), will cease because the culmination of God's love for his creation will be fully comprehended. The reason for the ceasing of things like prophecy and tongues is because their purpose will be terminated by the presence of the One in whom they point to...all that will be left is Love unsurpassed and unhindered in the ultimate of intimacy: face to face fellowship everlasting with the Godhead.
Talk about a Valentine's Day...
Soli Deo Gloria,