It's next to impossible to put words to it exactly.
You can't tell another person how to do it.
You can't even tell a person exactly how to love you.
Sometimes it's actions, sometimes not.
I think it has a lot to do with integrity and trust.
I think you can't be the boy who cried wolf without consequence.
A person will only allow themselves to be opened up for that kind of chain yanking for just so long before they shut themselves off. It's always a horrible shut off. Sometimes we just say, well, I don't like you, I still love you because you're my XYZ label in life, and you do, in a way, but the thing is done.
We protect ourselves when we have to.
It's often the unspoken words that do the damage. The intent.
Everyone has that camel's last straw moment when they hear "I give up on you, on this love".
As a foster parent, I watch each one of my kids hit that place with their parent. Hardly ever does a parent actually say those words, but it's there. It's clothed under the "I love you but..."'s. What ever comes after the but is the only thing the child hears and no matter what the word arrangement, they simply hear, "I quit, I give up, it's too hard to be your parent, you're not worth my effort".
None of this is to say there won't be continued contacts or life long back and forth; there will be. It's how it is. The tie is there no matter what. Sometimes there is a certain kind of friendship achieved. It's a polite thing. A thing at arms distance. It's tinged with a certain sadness about it.
Love is a thing we spend all our lives wanting and giving.
Sometimes it has a split second that feels perfect.
Sometimes there is a long season of really good.
Always, it's really hard work.
Always it finds it's solid ground in being able to keep the other person perspective bigger than the personal feeling or slight.