where are you located? better chances of finding what you are looking for in SD or santiago than anywhere else in the country. don't get so snappy at "gringo thing" comment, couple therapy is still relatively knew and many dominicans do not like to include outsider in their relationship problems.
in any case, i am a huge fan of clinica union medica in santiago and i see they actually have there a doctor that specialized in couple therapy, melissa rivera. why don't' you give her a call or send an email? here is the link with her details and bio:
Melissa Rivera, MPsi
she's young so there is a good chance she speaks english.