Can my real estate agent be held liable for breach of fiduciary duty for disclosing information to a relo co.?

I specifically told my real estate agent that I would not be replacing the siding on my house and not to tell my relocation company that I would. The relo company made an offer and during the time that inspections were being conducted, they requested a report from the real estate agent without my knowledge. She told them in order to sell the house again within 30 days, the siding needed to be replaced, which would cost about $25k more than I can spend. They then demanded that in order to complete the offer I had to re-side the house, which I cannot afford. Because of the pending offer with the relo company, I turned down an offer for the house as it was for slightly less and now am being forced to sell for much less than either offer. Did she breach her fiduciary duty by not obeying my wishes and undermining the entire process?

If this was a "dual agency" where she represented both parties, you may have waived your right to have anything kept confidential.

Real estate agents are regulated by your state. Contact the state licensing board and ask them your question.

It will boil down to the regulations of the state you are selling in. But, in principle, there does appear to be a strong conflict of interest present here. In addition, the agent should have had nothing to do with your relocation company.

Depends on the state and your relationship to the real estate agent.

Is the real estate agent the one that you listed with, or one representing a purchaser? (Can't really tell.)

Are you in a state that recognizes the difference between buyer's agents and seller's agents? Or are you in a state where the agent can be both at the same time?

If you specifically told a seller's agent not to disclose something, and they did, then yes, they may be liable for the breach. However, this must be weighed against your duty to disclose defects or latent defect to a purchaser.