Summer lovin' happened so ... swiftly.

In the span of just seven days, Robert F. Kennedy's grandson Conor Kennedy went from near obscurity to dating the hottest country star in the nation, The Post reports.

The couple were seen kissing, holding hands and getting extremely "touchy-feely" last weekend at the exclusive Kennedy compound in Hyannis Port, Mass., according to a witness.

Swift arrived at the compound last Friday around 5 p.m., the source said. She rented a small house on the property - a requirement for guests by the property's managers at the Edward M. Kennedy Institute.

Soon, the singer and Conor, the son of Robert F. Kennedy Jr., and the late Mary Richardson Kennedy, were spotted playfully bouncing together on a trampoline with a large black dog.

Later, they went to a house party down the road where Swift's presence turned heads - even among the local, jaded Kennedy watchers.