When expressing romantic feelings towards someone, it's common to use the phrase "object one's affections." However, there are many synonyms that can be used to describe the same sentiment. Some more formal options include "declare one's devotion," "profess love," or "express ardor." For a more casual approach, one could say "show affection," "have a crush on," or "be sweet on." Other synonyms could include "adore," "care for," "treasure," or "cherish." Ultimately, the choice of which synonym to use will depend on the tone and context of the situation, and how comfortable the person is with expressing their emotions towards the object of their affections.
