Will-they-won't-they

Princess Sonja, the daughter of an Oslo fashion house director, married Crown Prince Harald last summer after a will-they-won't-they romance that had gone on for a decade.

Source: wiktionary

Duet is a "will-they-won't-they?" sit-com about a young couple best described as in the throes of 'courting'.

Source: wiktionary

Woolworths had already started manufacturing wedding memorabilia, including William and Kate china, ahead of an announcement; the press toyed with the will-they-won't-they question; and the couple kept a chart of newspaper speculations on the royal wedding

Source: wiktionary

Ôba's three-part What is Your Name? (Kimi no na wa, 1953—1954), a will-they-won't-they romantic drama in which a couple meet on a bridge during a wartime air raid and fall in love, promising that they will meet again although unfortunately neglecting to tell each other their names, was the most commercially successful film of the early 1950s.

Source: wiktionary