Hmm, do you mean you didn't think about Lestrade on the way to the ball? That shouldn't affect things too much. Though I still recommend replaying from ch4 or the start once the full ball is out, as there's a bunch of new variables that might not be recorded otherwise!
If you did think about Lestrade, you can choose a:
#But I know it will never truly be the same (remove all romance points and clear the romance)
This does reset and remove the romance, and maybe not forever, but it will be harder to get back into it.