Love can only be fulfilled within oneself. If we are in Christ and he in us then we will understand the greatest commandment of love. Christ did not fulfill a commandment that states to love, but only made a proclamation of which was the greatest commandment in the law. To fulfill something means to make an end to or accomplish that that needed to be finished. How did Jesus fulfill love? Is love finished or do we continue in it?
Young's Literal Translation
Mat 5:17 `Do not suppose that I came to throw down the law or the prophets--I did not come to throw down,
but to fulfil;
Mat 22:36 `Teacher, which is the great command
in the Law?'
Mat 22:37 And Jesus said to him, `Thou shalt
love the Lord thy God with all thy heart, and with all thy soul, and with all thine understanding--
Mat 22:38 this is a first and great command;
Mat 22:39 and the second is like to it, Thou shalt
love thy neighbour as thyself;
Mat 22:40 on these--the two commands--
all the law and the prophets do hang.'
So we see that these two commandments are in the Law and all law hangs on them.
So were the sacrifices for atonement in the Law? Yes. So even they must hang on love.
How could something be accomplished and yet continue on? Certainly all things are possible with God. But I can think of something of this earth (well kind of, I believe it comes from God) music.
Bach composed music over 200 yrs. ago. He accomplished many beautiful pieces. One of my favorites is Cantata No.66. Whenever an ensemble plays and sings his compositions his music continues on through those artists even though he accomplished the finished work 200 yrs ago.
When we walk in the Spirit, loving God and our neighbor, Jesus' finished work continues on through us. Not by us but through us.
His love continues on. He blesses others through us. He edifies through us. His words, His gospel is proclaimed through us.
1Co 13:13 and now there doth remain faith, hope, love--these three; and
the greatest of these is love.