How could I forget?

Some people say
Only men will forget
But that's not true
And with that fact I regret
To tell the tale of that night,
On the fifth of December
when I forgot my anniversary
I had always remembered!
It had been a long day,
and for reasons so weird
I called up my boyfriend
and I said, "Hello, dear,
"I wonder if we can skip
our date tonight,
I've made other plans
to hang Mom's Christmas lights!"
He sounded so distant,
Upset in a way
but he sighed, resigned,
and he said OK
The next morning when I woke
The light bulb came on
I felt then, so stupid
And I called his cell phone
"Oh, baby, I'm sorry,
will you ever forgive
this unthinkable deed
That I won't to again?"
I cried to him softly,
and he said quite stung,
"Of course I'll forgive you,
but what have you done?
I can't think of anything
you did to upset me, but
by the way, babe
Happy anniversary!"