When it comes to synonyms for the phrase "leave behind", there are quite a few to choose from. For starters, one can use the term "abandon", which implies a sense of desertion or giving up entirely. Similarly, "forsake" conveys the idea of abandoning someone or something, often as a result of disapproval or disappointment. "Forget" is another option, suggesting the lack of remembrance or attention. It's worth noting that all of these phrases can have negative connotations, as they all suggest some form of separation or neglect. However, depending on the context, they may also simply imply moving past something or moving on to something new.