Is it a man thing or a MY man thing?

We have a gathering to attend tomorrow night for a friend's birthday.  We've known about it for about two weeks now and yes, it's been marked on the calendar.  

Friday hubby calls from work and says that *so-and-so* (another guy at work) and his wife have invited us over for Sunday evening.

I told him that was nice, but we were going to be at the birthday party, remember?

Oh, yeah, I forgot about that.

Now - here is where the question lies:

If I were the one at work I'd have immediately gone over or called over to the guy's office and told him that, hey, I forgot, but we have a party to attend at that same time, sorry.

Did he do that?

You are correct.  He did not.

A few minutes ago I was looking for wrapping paper for the present and hubby says I guess I should call *so-and-so,* huh?

WHAT???

You haven't told him that we can't come yet?

No, why?

What if they bought a bunch of food to cook or turned down plans of their own or something?  You should have told him Friday.

Hubby:  "He has my number, too."

Me:  "Yeah, he used it to INVITE you.  After that, it's on YOU."

Geesh.

I found the wrapping paper and left the room.

About 10 minutes later hubby comes in the living room:

"I told him we'd probably be there around 7:00 or so."

Let's see.

The party starts at 6:00.  There will be dinner and general visiting and just relaxing to have a good time.  They are planning on a bonfire AT DARK if weather allows.  You know, 8:30-9:00 PM?  

Excuse me while I go bang my head on the wall.