It's That Time of Year by Roisin Meaney

It's the day before the wedding ...
Three strangers arrive home to Ireland to the house that gave each of them refuge when they needed it most. They are there to celebrate the winter wedding of their beloved Annie, the woman who fostered them in their childhoods.
Now Julia is a world-famous singer living in luxury in Paris and Eddie is a chef in London, while Steph spends her days on a remote Greek island, running a writers' retreat with her older lover.
All three have moved on from the past, but as the wedding celebrations get underway, certain truths come to light. It turns out that some hurts last longer than others ...
As Annie says 'I do', with an unexpected twist for her wedding party, will Julia, Eddie and Steph discover their own happy-ever-afters in time for the big day?