From Longman Dictionary of Contemporary Englishbe involved with somebodybe involved with somebodya) SYSEX/HAVE SEX WITHto be having a romantic relationship with someone, especially a sexual one The senator denied that he was romantically involved with a member of his staff. b) to spend time with someone that you have a relationship with Fathers are encouraged to be more involved with their families. → involved
Examples from the Corpus
romantically involved• A boss who is romantically involved with a subordinate can exhibit favoritism through raises, promotions, assignments and the like.• At the same time, she becomes romantically involved with the hero.• While an undergraduate he became romantically involved with various members of the Bloomsbury group. 