When a boy and girl become best friends, the platonic nature of their relationship can become an immovable barrier between them.

Even if they both make mistakes with other partners and seem to be more right for each other than the alternatives, the will-they-won’t-they feeling never seems to reach a tipping point in their favour.

On her 18th birthday, a delirious and drunken Rosie (Lily Collins) shares a smoldering kiss with Alex (Sam Claflin) but forgets about the smooch thanks to a bump to the head.

He doesn’t forget and jokingly skirts the issue of romance, which Rosie shoots down by quipping, “You will forever by the guy who wiped bogies on my party dress.”

The film then goes into flashback mode to explore their past lives as a signpost for possibly, just possibly, getting together in the future.

Except that Alex going off to Boston complicates matters enormously.

Directed by Christian Ditter (The Crocodiles), the film is a pleasant enough, light-hearted watch and the end justifies the means.

But the journey is uneven.

Echoing Nebraskan writer Nicholas Sparks’ ability to turn modern romantic literature into movie fiction, this is the second major adaptation of one of Dublin-born novelist Cecilia Ahern’s novels.

Unfortunately, Love, Rosie seems to be a younger-cast carbon copy of PS I Love You (2007), which saw Gerard Butler misfiring opposite Hilary Swank.

It’s just another eye-candy formula film with a capital F, right down to Claflin’s Hugh Grant-style grin and the PS-style dual-continent story (which has less purpose than Daniel Radcliffe’s recent US-to-Dublin romcom What If).

While the comedy of errors set-up is timeless, there are no more surprises than a box of Cadbury’s Roses – which might, of course, be exactly what you’re looking for.