The phrase "shares bed and board" is commonly used to imply that two people live together and share their home, both its physical space and its expenses. There are several synonyms for this phrase that can be used interchangeably, depending on the context and tone of the discussion. Some of the most popular options include cohabiting, living together, shacking up, and rooming together. Each of these phrases has its own nuances and connotations, so it's important to choose the most appropriate synonym for the situation at hand. Regardless of the specific wording used, the underlying meaning remains the same: two individuals are sharing their lives and resources in a mutually beneficial way.