Lovebirds was a term used to describe people who were in love.
In the 2372 premiere episode of A Briefing with Neelix, Neelix described a operations lieutenant and a sciences crewman on the USS Voyager as lovebirds, wishing them all the best. (VOY: "Investigations")
In 2374, Vic Fontaine described Odo and "Lola Chrystal" as lovebirds, asking if they could manage without him. Later, after "Lola" was found to be Kira Nerys, Vic defended his tricking both of them, as he had "brought you two lovebirds together", which was the whole point. (DS9: "His Way")