A dream about an ex-boyfriend, ex-girlfriend, ex-husband, ex-wife, etc. can mean:
You have unfinished business with this person
You are fondly remembering something about the time you were with them and that you'd like to experience that feeling more in your current lifeābut most likely not with them
Your current romantic partner, or an imagined or desired partner if you're not currently in a relationship
Possible dream symbol meanings in the dream dictionary are suggested. No "standard meanings" exist because dream meaning is subjective and specific to the dreamer.