if your antenna first went up about a month ago, and you've departed for and returned from an international trip since then.

I do sympathize with the way this has been bothering you so much you've even dreamed about it :( That's sad. I think your girl would/should want to know that.

There's only so much a stranger/outsider can say, since we don't know yall. But ya I think you're displaying clear symptoms of need-to-communicate-itis. You are bottling this trust issue up inside you and it is not only making you feel uneasy, but it could be affecting other areas of your relationship/communications too (you say you two have been having a rough patch lately).

I also think it might help to just take some deep breaths over this, and ask yourself even IF she was feeling connected to dude, how deep could such a connection get in the span of a few weeks.

But judging just from my own personal work sis view?? If it was me it would literally just be some funny dude from training that I'm telling my man about *shrug* You mention below that you're going to a hh with them tomorrow, and I think that's PERFECT. I think work friendships become waaay more sustainable when the SOs know everyone.

There's a risk that making the friendship a "thing" could multiply into more and bigger fights down the road, unless you anticipate her quitting the job she JUST got that she's CLEARLY enjoying, making friends at, etc.
So ya. I say think about what's sustainable here. Not just for the two of you, but for you personally. It may not actually be your relationship.