"Why can't you love me?" he scowled.
"I can't, I've never seen you that way. How difficult is it for you to understand?" She frowned.
"I can't love you when I know you're not that piece of my puzzle." She responded with a heavy heart.

You fell in love with her. You fell in love with her smile. You fell in love for how beautiful she is on the inside. There maybe some unspoken rules of Love. But the necessity of loving someone back is not one of them.

Your jealousy is strong. When you see her in someone else's arms, you go insane.

Is that love?
Or is it love that keeps you sane.
Instead of driving you crazy, it'd make you realize she's a free bird who has just found a new cozy nest and deserves to live in it.

I think it is just unfair how she thinks of your feelings before she cares about her own.

Ever asked her why?
It is because you were there for her.

Every time she needed someone to talk. Every time she needed a little light to see through the darkness in her life. You were there. Hence, She CARES about you.
Love is not something you can force out of people. It's a feeling that grows like a plant. You cannot expect her to give you mangoes when all she has are flowers. This is the way it is and YOU, you need to accept it.
When you love someone, you don't pass over an obligation to love back. Love is just given to someone you care about because you want to, because you think they deserve it. When did loving someone turn into a necessity of relationship? When did we slowly start to forget those other bonds of trust and compassion those held people together? Your love isn't strong as you claim it to be if you see destruction of your own happiness when she doesn't choose you. You're scared about being hurt. She is too, while she's hurting. Can you handle that if you were in her place?

When she finally removed all the thorns of her past and found roses, all you do is lead her to a new field of cactus?

Is that what your love is?

She is weak they said. Yes, she is. Weak as she cannot choose her hurt over your feelings. Weak as she cannot push you away with all your feelings. You matter to her but you do not know that. You're blinded by jealousy.
There's a saying about there being a thin line between friendship and love. Either way, both the relationships are beautiful. You just need that heart to feel it and eyes to see.