mixed up with

*mixed up with (someone else)

involved with another person, possibly romantically. (*Typically: be ~; get ~.) I hear that Sam is mixed up with Sally. Who is Jerry mixed up with now?
See also: mixed, up
References in classic literature ?
Mixed up with many striking, thoroughly dramatic physiognomies, it must be confessed that some of these portraits scarcely help at all to explain the power of the players to whom they belonged.
A WOMAN was given the wrong cancer treatment after her lab results were mixed up with another patient who had the same initials, an inquest heard.