Maybe he likes that song, and the words are well written. He might send it out. No other meaning, maybe just as you suspected. This is hard to say. We can talk more together, make a joke, or politely ask him some answers you want.
With the development of love, the concept of boyfriend in people's minds has developed from a single male friend to a male partner in a couple. Now people's understanding of boyfriend: he is a man you love.