he/she he went out with

This is a very knotty problem.

Technically, the verb "to be" does not take an object, and so strictly speaking we should say "it was she".

But that's not what we say, most of the time. We say "it was her." I think common usage must trump the laws of grammar on this occasion.

The correct usage is widely disregarded these days.

I remember a story in one of the "William" books by Richmal Crompton, where William's mother asked who broke a window. "It was me" said William, and he was surprised because his father said " It was I ".

That's not the correct usage, Contrex. It's but one usage available to English speakers.

You're right. I should have placed "correct" in quotation marks.