The couple attended pal Ellie Goulding's nuptials in Yorkshire, England on Saturday (August 31), and sources claim Katy and Orlando are also heading across the Atlantic to tie the knot after becoming engaged in February.
They're considering Ashford Castle in Ireland for the wedding.
An insider tells the National Enquirer: "Katy and Orlando are looking into tying the knot at a Gothic Irish castle. It's going to be a fairy tale extravaganza."
And while the "Dark Horse" hitmaker is planning to take care of the nuptials without the help of a wedding planner, she's asked "her inner circle of assistants, stylists and tour stage designers to pitch in where needed."
The couple is currently building on its relationship before tying the knot, as neither Katy nor Orlando wants to get divorced again.