is never, ever, ever ... gonna be more than a stone's throw from the Kennedys ... because TMZ has learned, Swifty DEFINITELY bought a mansion next door to their famous Cape Cod compound.
According to a local realtor ... Swift 100% will be moving across the street from Ethel Kennedy
-- despite reports to the contrary. The realtor tells us the singer dropped around $4.5 million on the beachside mansion in Hyannis Port, MA.
As you know ... Taylor and 18-year-old Connor Kennedy
-- grandson of the late Robert F. Kennedy
and Ethel -- started dating
a few months back.
Our sources tell us the deal will close in 3 weeks.
As for the crib -- we're talking 7 bedrooms, 6 baths, over 4,400 square feet, an acre of land and its own private beach.
Where she can write songs about ... not breaking up?