What does Andy think really happened to his wife and her lover?

Screenplay

ANDY
My wife used to say I'm a hard man
to know. Like a closed book.
Complained about it all the time.
(pause)
She was beautiful. I loved her. But
I guess I couldn't show it enough.
(softly)
I killed her, Red.

Andy finally glances to Red, seeking a reaction. Silence.

ANDY
I didn't pull the trigger. But I
drove her away. That's why she
died. Because of me, the way I am.