There are plenty of synonyms for the term "live in lovers". Some common alternatives might include the phrase "cohabiting romantically," "domestic partners," or simply "roommates with romantic benefits." Other terms that could apply might include "committed partners," "spouses without marriage," or "long-term companions." Depending on the specific relationship and cultural context, there may be a variety of other phrases that could accurately convey the same idea of two people who share a living space and a romantic connection without being married or formally committed. Ultimately, the most appropriate synonym for "live in lovers" will depend on the nuances of the individual situation.