You should not make someone uncomfortable with your romantic interest.
Dave and his wife, who doesn't speak good English, are visiting Dave's mother, who doesn't speak Dave's wife's language.
Dave wants to speak with his wife.
Dave and his wife speak in English to include his mother.
Dave and his wife talk in his wife's native language, leaving his mother out.
Dave's mother feels happy and connected with Dave and his wife.
Dave's mother feels very awkward and offended that she's not included.