Oh OK I actually get to do the whole brief history lesson on Haitian-Dominican Relations. Haiti and the Dominican Republic were once colonies each, Haiti a French colony and the D.R. a Spanish one. Haiti got their independence in a bloody slave revolt, and their independence came with crippling debt imposed by France, near complete exile from the global economy, and a series of violent political coups since Napoleon had betrayed and ordered the assassination of the one guy who might have been capable of holding the country together when he travelled to France to negotiate peace. Not to mention a driving ideological force of the revolt was literally voodoo, so all in all not a recipe for success.
The Haitians eventually decide to try and unite the island under their rule, and invade and subjugate the then-independent Dominican Republic on the other side of the island. The Haitians try to forcibly integrate the Dominicans with a program of cultural erasure designed to force French/Creole on the Dominicans among other things. This doesn't go well, the Dominicans fight back and win their independence again, and never, ever live it down.
Years later, dictator Rafael Trujillo would initiate the Perejil Massacre targetting ethnic Haitians in the D.R. as a sort of historical revenge, becoming notable in history as a genocidal incident that occurred incredibly close to the US, with implicit US support since the US propped up Trujillo's regime as it did others in the America.
There's a lot more to it, I may have butchered a fair bit, but since the Perejil Massacre and death of Trujillo, things have improved and trade flows nascently between the countries, but there's still a bitter legacy to contend with.