This is a song where the composers could have left the chorus as a single refrain line that happens at the end of the verse. It's a super dynamic line and would have sounded nice even if they'd just left it alone. Abba, instead, repeat the line with new rhyming words, giving them a chance to keep clinging to the chorus' precipice.
That's even nicer, but they don't even leave it there. Line three comes in next like another repetition, but then diverges, necessitating another line that rhymes with it and concludes the phrase. Harmonically, they're now set up for the return once again of the refrain line, heard now with a third set of rhyming words. This, in turn, allows them a consequent phrase, for which they finally repeat the original refrain.
All of this plays beautifully into the premise of disco as a music that relies on repetition, a forty-five second long chorus flourishing where some songwriters might not have had much of one at all.