Could be. In the end I guess we simply don't have enough canon characterisation for Jack in this era to say anything with any certainty. Like I said to rm, I just can't quite see Jack actually being willing to walk up to the altar and consciously make a promise based on a lie, especially not if he loved her. For me that's too much cognitive dissonance even for Jack. On the other hand, if she was a Torchwood employee and knew about him, and for whatever reason (maybe it was a practical thing, not a big love thing) they decided to go ahead anyway, and were making jokes about the whole 'till death do us part' thing... that I could definitely see.

In any case what I think stands out is that the wedding picture is the last in the pile, clearly the oldest one. After that it's only ever Jack alone. The link/contrast between the wedding picture and the way Jack steps back and lets Gwen marry Rhys is probably deliberate.