The terms A-side and B-side refer to the two sides of 78 and 45 rpm gramophone (phonograph) records, whether singles or extended plays (EPs). The A-side usually featured the recording that the artist, record producer, or the record company intended to receive the initial promotional effort and then receive radio airplay, hopefully, to become a “hit” record. The B-side (or “flip-side”) is a secondary recording that has a history of its own: some artists, notably Elvis Presley, the Beatles and Oasis, released B-sides that were considered as strong as the A-side and became hits in their own right. Creedence Clearwater Revival had hits, usually unintentionally, with both the B-sides of their A-side releases. Others took the opposite track: producer Phil Spector was in the habit of filling B-sides with on-the-spot instrumentals that no one would confuse with the A-side. With this practice, Spector was assured that airplay was focused on the side he wanted to be the hit side.
Contemporary pop charts such as Billboard’s Hot 100 are based on radio play and digital downloads, which do not have “sides”, so the terms are becoming antiquated.
Let me add here that the concept of love is never going to be antiqued. There are always polarity of things and there will always be for the universe to work in harmony. The thing is to play it cool 🙂