Yes, your denomination teaches this. As dogma.
Lots of denominations teach lots of things. Are they always, automatically, categorically and unquestionably correct? Or just yours?
If you make a statement of fact and as dogma, you should not be surprised or offended that others ask for some substantiation.
It's true that some later church father's believed this. Many Christians - including Luther and Calvin - did/do. But that's not the issue we're discussing. We're discussing if it's true.
Yes, your denomination teaches it. But the Bible, the noncanonical book you suggested, and the earliest church fathers do not. There is no evidence that it "was always taught" - much less as dogma. But you don't seem to appreciate that YOU are the one with the dogma on the issue of how often Mary and Joseph did it together after Jesus was born. YOU are the one saying it's a fact. YOU are the one saying it's of highest certainty and importance and must be believed. It's YOUR dogma. You shouldn't be so troubled that people ask you for verification. And you shouldn't be surprised that others do not find as compelling, "But my denomination says it's right!" anymore than we would if a JW or Christian Scientist used the same defense and substantiation for the denomination's teaching. I hope you can appreicate that. Because YOU are the one insisting that they never did it - not once - and that you are dogmatically certain of this. It's YOUR view.
Thank you.
Pax!
- Josiah