Can we be "too nice "? Is it possible to love too much? Not in my experience. When I was a small boy I was taught to love my neighbor as myself. The old "Golden Rule"; do unto others as you would have them do unto you, was the credo of my family. My Father would bring home the homeless and hungry. My Grandparents, who ran an apartment building, would have the whole building in for Thanksgiving and Christmas. They had even done this during the Depression, and believe me, they were poor!. Love was a visceral feeling in my home and in my life.
Today, psychology, and some philosophy would want you to believe that you need to "love yourself first" . There are those psychologists who believe that we "hate " ourselves, and therefore "seek " outside of ourselves for love. And of course, the "teachers " of non-duality, want us to concentrate on the "I am ". and love our "self " so we see through the false self to the inclusion of the "other ". These often simply become excuses for abiding in our selfishness.
This idea that, if I love myself, I am loving others, because we are all one, is a snow job. It's selfish. If we are all one, then loving others is loving yourself. This is also much more to the point and a safer position. It is much more difficult to love others as yourself, than to love others through yourself. We all start from a position of "I am ". This is the seed of selfishness. To lose your "self " in the love and service of others, is to find the "Self " that lives in us all.
My Mother used to tell me a saying my Great Grandmother used to tell her; "Brighten the corner where you are." An old fashioned saying for sure, but well remembered all the same. Bringing light, living as Love, this is what we are called to do. This does not mean using our minds to make judgments of who is pure or "loving ", but always being loving, even in the face of what appears to be evil.
The story is told of a robbery at Ramana Maharshi's Ashram. While many panicked, The Maharshi, even though mishandled by the intruders, told others to let the robbers have what they wanted. This was not out of fear, but out of loving kindness. The Maharshi was loving kindness itself. He had no choice but to follow his nature.
When I was a boy and in my teens, others would often tell me that so and so was taking advantage of me in some way. I would simply answer that I was aware of what was happening, and that no one could take advantage of me, as there was nothing that was "mine " that could be taken away. If you know who you are, you do not fear being taken advantage of, you have nothing to lose.
We can not stand as the "self " and make demands for "space ", or property, or even personal "peace ". If life, "God ", Love, sends into our lives "others ", then, if we are true to Love itself, we accept what is sent, no matter how "flawed ". Jesus, bleeding and dying on the cross, after suffering brutal humiliation and apparent "human failure ", said "Father forgive them, for they know not what they do." Those who "hurt " us, or "ill use " us are only engaging in Love in a "perverted " sense; self love, self protection. Our casting them aside, putting our own purposes and "self " protection before our love for them is no different.
The Christ's prayer at the Last Supper asks that the disciples "love one another " as he had loved them. How was that? How did he show his love for them? He hung on a cross and died. Ramana allowed his meager possessions to be stolen. Submission to life's situations is flowing with love. To hate another, to cast away another is selfishness, no matter what pretty philosophical or psychological bows you wrap it in.