The phrase "annoy with sweetness" refers to a feeling of irritation or frustration that comes from someone being excessively sweet or overly affectionate towards another person. Synonyms for this phrase might include cloying, syrupy, saccharine, or sappy. Some people might also describe this behavior as being overly sentimental, mawkish, or cheesy. While this type of behavior can sometimes be endearing or genuine, it can also come across as insincere or manipulative. In some cases, it may be best to simply have an open and honest conversation with the person in question about how their behavior is making you feel, rather than resorting to passive-aggressive responses or snarky remarks.