While bowling, Lowe and Giudici were "really lovely, high-fiving even when Catherine's bowling ball went straight to the gutter," an eyewitness told the magazine.
The couple had also been spotted on a date at the Ainsworth Park in New York City on Monday night in which they were allegedly overheard discussing a potential pre-wedding honeymoon.
Lowe had previously mentioned getting married this summer was a possibility for the couple.
"We've kicked around some ideas. It could be this summer," Lowe told People in March shortly after The Bachelor's seventeenth-season finale aired on ABC.
While the reality dating series was airing, a source told Life & Style in February, "Sean and his fiancee are happy and committed to each other. They're planning to get married before the end of the summer."
(Photo credit ABC)
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