Why do our hearts betray us?

There other day, at physical therapy, I talked with a beautiful lady whose fun, short, wavy, perfect hair I was coveting. She told me she hacked it because she is going through a divorce and in her bright blue eyes that can't hide her pain I saw pieces of me.
Hacking hair as a way to severe -almost literally- the attachments to boys who did not value. That was a pattern of my past that I did not really think was a pattern until I saw a mirror of me in this lovely lady.
That was something interesting, but the thing I saw in her that stirred me the most was her pain as she spoke of her exes. This lady loves and loves deeply. She is beautiful, lively and fun. But she is also in deep heart-wrenching pain. I know the pain. I can see it in her and I know it but I cannot feel it right now. I cannot allow myself to feel it again. I will not. I cannot take her pain and I know this, so I don't try to.
Instead I want her to feel the love I think she deserves to feel but I can't give that either because it is not my place and I am not the person for the job anyway.
Heartbreaking.
And I am struck with confounding wonder about our hearts that are so treacherous at times.
How is it we can love and be hurt so deeply?
How is it our human hearts can love so deeply and completely somebody who does not return it?
We are told to trust our heart but I am beginning to wonder if this is very smart, as treacherous as they can be.
They betray us.
Why?
This is so confusing to me.
Like the way that it felt like a dagger puncturing and twisting so many times over so many months.
How do we survive?
Our bodies are so strong and resilient
and yet I am positive these breaks take there toll.
I hope this beautiful lady finds a love that will last and bring joy that is equal or better than the pain she is feeling right now. ..and yet if she does, eventually one will be lost at very least to the process of mortality and then a heart will be deeply wounded again. Which is probably the real reason no one lives forever in these mortal frames.
May our hearts be settled in forever and until then I pray they may bare the burdens of breaking, time and again.
And I pray we will be kind to each other.