You haven't provided enough context for a serious attempt at an answer, so here's an imaginative fling:"That's true, and she started stomping grapes
with the old Count, and I was off the label."
What does with the old Count, and I was off the label."
"Off the label" could be a euphemism for dumped, as in the fact that she chose to be with the old Count and not the speaker. That is, if someone is "on the label," it could be a reference to the fact that that person's name appears on the label of a bottle of wine. Clearly, that person would be an established part of the family that produced that wine. So, if he's "off the label," she's basically telling him to take a hike. She's chosen to be with someone else, namely the old Count. He is no longer, or will never be, an established part of her family, if you catch my meaning.
P.S. This is about the best you can expect when you ask a question about a book you are reading without providing any context.
Student or Learner