There are various synonyms for the phrase "fall again into," depending on the context of its use. Some possible options include "relapse into," "slide back into," "retreat into," "regress into," and "revert to." Each of these synonyms conveys a slightly different nuance, with "relapse into" suggesting a recurrence of a negative pattern, "slide back into" implying a gradual loss of progress, "retreat into" indicating a withdrawal from previous gains, "regress into" suggesting a return to an earlier stage of development, and "revert to" implying a return to a previous state of being or mindset. When choosing a synonym for "fall again into," it's essential to consider the exact meaning and connotations desired in the context of the sentence or phrase.