You say Jesus said to be perfectly Loving like God.
God wants us to become perfect like He is in love and how He loves, but in this life, I understand and mean, we are going to always be in the process of correction in this direction. And so, we always will still be capable of sinning. . . somehow. I do not mean that in this life Jesus knows we can become perfectly loving like God.
And I think we have support for the fact that we can still sin, because in Ephesians 4:32 our Apostle Paul says for us to forgive one another >
"And be kind to one another, tenderhearted, forgiving one another, even as God in Christ forgave you." (Ephesians 4:32)
God does not tell us to forgive each other for what is not a sin, I would say
Lets say that someone reached the height of this command....and they are perfectly loving...like God (lets just assume this is possible for the sake of less argument) Can you give me a "Sin" that this person could commit?
So, in this life, I do not understand that one will or can reach the height of this command. But what I would offer, sort of in answer to your question, if I understand you right, is >
As we grow in Jesus love, there are the more obvious sins which we do stop doing. But then we discover things we did not know are sins. And so we go on to seeing how we need correction which at first we did not know we need.
In my case, for example, I have sinned against love, by expecting attention and recognition for being a teacher and preacher. I did not have a clue that I was wrong, like this.
Also, I have been able to only use people, instead of first personally caring for each and every person.
So, as I grew in love, I more and more realized what is anti-love. And so now what I consider to be sinning has developed. I might stop some number of more obvious sins, but then the standards get higher, I guess you might say