Taylor Swift's recent breakup with DJ/producer Calvin Harris was definitely one-sided, a source close to Swift tells ET.
The source believes 100 percent Harris was behind the split and that it was not mutual. "A few weeks ago she was talking about marrying him," the source says.
Still, Swift seems to be just fine after the breakup. The 26-year-old GRAMMY winner crashed a New Jersey wedding on Saturday to sweetly surprise a fan with a performance of "Blank Space," after the groom's sister reached out to her in April about their mother's death. Swift appeared to be in good spirits as she surprised Max Singer and Kenya Smith at their nuptials at Brandt Beach Yacht Club, upon learning that the two heartbreakingly married earlier in Singer's mother's hospital room so that she could be a part of the occasion before she died. The groom and his mother chose "Blank Space" as the song for their mother-son dance, and Swift fittingly performed the tune on piano for the newlyweds' first dance on Saturday.
WATCH: Taylor Swift Surprises Fan With Performance at His Wedding As Calvin Harris Takes on First Post-Split DJ Gigs
Meanwhile, 32-year-old Harris was also all smiles on Friday, when he was spotted at a medical clinic in Beverly Hills, California. Last month, Harris was involved in a car crash that briefly landed him in the hospital, and forced him to cancel a few of his scheduled performances in Las Vegas. Harris returned to work at Las Vegas' Omnia nightclub on Friday night, where he performed a nearly two-hour set. On Saturday night, he had dinner with singer Frank Ocean at Nobu restaurant in Malibu, California.
WATCH: Taylor Swift and Calvin Harris Split -- What Went Wrong?
"The only truth here is that a relationship came to an end & what remains is a huge amount of love and respect," Harris tweeted last Thursday, when he addressed his breakup with Swift for the first time after more than a year of dating.
Showing there's no bad blood, Swift re-tweeted the amicable statement.