A slightly different takeon this, especially it you're both adults.
You had company and you went off to work on a model? Do I have that correct? That's just plain rude. It happened a year ago and you're still bothered by it. Something wrong with this picture.
I'd be pretty upset, too, if I went to see a friend and instead of sociaizing with me he went off to do something that didn't include me. You messed up, you were both wrong. , you need to let this incident go.