Just remembered an example in my own life. When we first got together, my current partner started calling me "Junior." My full name doesn't have Junior in it, and at that time I was already 58, hardly a kid, though he is older.
Plus, I knew his beloved late dog, whose framed oil portraits are all around here, was named Junior. I realized he used it from affection, but I didn't want to be called by the name of his dead dog, whom some of his current friends had known, nor anything that seemed to make me something of a "junior partner" in the relationship.
Whether or not I was being overly sensitive is not the point here. The point is that I didn't like that nickname, and I already used another by which everyone knows me. I requested he drop Junior and either call me by my regular nickname, or come up with something else. He understood and agreed.
Nevertheless, for a while he still slipped and would use Junior, and I'd try to diplomatically correct him. He's finally lost the habit. Now, however, he's started to refer to me by his late partner's nickname, or him by mine, which starts with the same letter as mine, and is likewise a single syllable, so I understand what's happening. I gently correct him without reproach, and given he was with the guy for about 17 years, I can't complain.