Why is it that i can't hold on to the things in life that i love the most?

What is it I’ve done in this life to deserve all this physical pain and mental hurt?
Why can’t I hold on to the things i love the most,
Instead of searing and burning Every thing in my life to a crisp,
You would think in life, 
By now I should have learnt.
In the space of a near year and a half,
Nearly everything in my life has changed,
All areas of my life except my three little bundles of joy,
But even they are threatened to live a life they don’t want to lead as my 3 little boys.
‘’ don’t let mum win, we love you and don’t ever want to leave your side’’
My three little boys didn’t even have to think of which path to decide.
So why in life is every one or thing  that i touch have to be dismantled and left out in the rain to rust?
Since my wife upped and left my three boys and I,
Everything I’ve touched hasn’t turned to gold but has wilted and died.
Everything even down to my perishing body,
As I feel myself decay,
And the threads and my seams are just withering away as it rots and it fades.
My five relationships ,
Each I thought would ever last.
But in the end,
All they’ve done,
Is piece by piece,
 ripped and torn my heart apart.
Some my own doing,
Some i didn't get.
But it’s this last one that's destroying me,
Bit by little bit.
Only three days have passed since things were ended.
But still each day that passes,
I just sit and stare and think of,
In 9 weeks,
All the love that we blended. 
It’s over now,
I’ve just got to get it in my head.
Not carrying it around,
My head dropped,
Like it’s supporting metaphoric tonnes of weight,
As I really thought in her,
My soulmate I had found.
Who knows we might get back together some day,
That’s just me hoping,
Cos it’s irretrievable,
Even I know that.
So please answer me this,
Why is it that i can’t hold on to the things in life that i love the most?