He's stolen her, and my happiness...

Why am I not allowed happiness?
Living my life under worry and stress:
Like a cloud hanging over, weighing me down.
Everything ends up a mess.

Is it how I walk, how I talk, how I am?
Frankly I'm determined to not give a damn
What people think of me, but sometimes, I fail.
From some my efforts are a sham.

In the end I don't get what I work so for,
A year (plus) of effort, and I'll get no more
Than what I have now. Should I be content
With this, and give up this dull chore?

Four days past, he was pest'ring
Her conscience to end. She was sequest'ring
Herself from him, complaining to me of annoyance.
Now they're "they", I'm left festering.

How does a mind so quickly change course?
Like lightning in skies, or a startled horse
She has leapt from annoyance straight to happiness -
Or so she says, but with too much force.

I love her, but cannot tell her this, not now.
She is with him, and I am furr'wing my brow
In consternation: what has he that I don't?
None, it's what he hasn't that's his bow.

He has not my tendency to overthink:
Delaying each choice even to the brink
Of insanity, but I cannot change this.
They're "happy", and my hopes are left to sink.

I cannot think on this problem longer
I would go crazy, and he'd still be with her.
I can't break them up, can't stand them together...

Why am I trapped in this hell?