This reading is a partial filleting of a larger article just to bring down its size.
The original article is "Metta means goodwill" by Thanissaro

...metta is not necessarily an attitude of lovingkindness. It's more an attitude of goodwill — wishing the other person well, but realizing that true happiness is something that each of us ultimately will have to find for him or herself, and sometimes most easily when we go our separate ways.

This understanding of metta is borne out in the Pali Canon, first of all in the word itself. The Pali language has another word for love — pema — whereas metta is related to the word mitta, or friend. Universal metta is friendliness for all. The fact that this friendliness equates with goodwill is shown in the four passages in the Canon where the Buddha recommends phrases to hold in mind when developing thoughts of metta. These phrases provide his clearest guide not only to the emotional quality that underlies metta, but also to the understanding of happiness that explains why it's wise and realistic to develop metta for all.

The first set of phrases comes in a passage where the Buddha recommends thoughts to counter ill will:

Notice that last statement: "May they look after themselves with ease." You're not saying that you're going to be there for all beings all the time. And most beings would be happier knowing that they could depend on themselves rather than having to depend on you.

Another set of metta phrases is in the Karaniya Metta Sutta. They start out with a simple wish for happiness:

But then they continue with a wish that all beings avoid the causes that would lead them to unhappiness:

For people to find true happiness, they have to understand the causes for happiness and act on them. They also have to understand that true happiness is harmless.

The Karaniya Metta Sutta goes on to say that when you're developing this attitude, you want to protect it in the same way that a mother would protect her only child.

Some people misread this passage — in fact, many translators have mistranslated it — thinking that the Buddha is telling us to cherish all living beings the same way a mother would cherish her only child. But that's not what he's actually saying. Instead of drawing a parallel between protecting your only child and protecting other beings, he draws the parallel between protecting the child and protecting your goodwill.

Metta is not necessarily the quality of lovingkindness. Metta is better thought of as goodwill, and for two reasons. The first is that goodwill is an attitude you can express for everyone without fear of being hypocritical or unrealistic. It recognizes that people will become truly happy not as a result of your caring for them but as a result of their own skillful actions, and that the happiness of self-reliance is greater than any happiness that comes from dependency.

The second reason is that goodwill is a more skillful feeling to have toward those who would be suspicious of your lovingkindness or try to take advantage of it. There are probably people you've harmed in the past who would rather not have anything to do with you ever again, so the intimacy of lovingkindness would actually be a source of pain for them, rather than joy. There are also people who, when they see that you want to express lovingkindness, would be quick to take advantage of it.

This doesn't mean that lovingkindness is never an appropriate expression of goodwill. You simply have to know when it's appropriate and when it's not. If you truly feel metta for yourself and others, you can't let your desire for warm feelings of love and intimacy render you insensitive to what would actually be the most skillful way to promote true happiness for all.