Romulans wanted no peace with the UFP. The UFP would've been at risk in allowing their alliance to develop as it was, because the Romulan goal was a shift in power to their advantage, over the UFP. The Durass sisters took orders from Romulans. They were Romulan pawns, not equals in a peace accord. An Empire ruled from Romulas is what Worf called it, correctly so.
The Durass sisters were not interested in peace accords with all sides. They wanted someone to give them military aid to help them in seizing power of the Empire. The UFP would not do that, but the Romulans would, because even if it failed, there was a chance of it destabilizing the region, & creating a weakness for the Federation