OK! EXCLUSIVE: Kim's Revenge Romance

Could Kim Kardashian's reign as Hollywood's sexiest single woman be over already? It certainly looks that way after the reality star was spotted enjoying an intimate lunch date with European soccer stud Cristiano Ronaldo in Madrid on April 16.

OK! NEWS: KIM KARDASHIAN — "I'M SORRY I DID PLAYBOY"

"Kim was visiting friends in Spain, and she saw him almost every day during her visit," an insider tells OK! of Kim's dates with the Portuguese Real Madrid player. "He is definitely taken by her."

A second source confirms that Kim feels the same way: "She thinks he's incredibly sexy, and she loves his body.

During their lunch, he even leaned in and gave her a kiss inside the restaurant. He is so smooth and so genuinely charming."

OK! GALLERY: KIM KARDASHIAN DONS STRIPES DOWN UNDER

However friends confirm that Kim and Cristiano's growing infatuation has caused jealousy and heartbreak for the couple's major love rivals.

"It made him jealous," admits a pal of Kim's ex-boyfriend Reggie Bush. But, adds the friend, Kim's revenge romance hasn't made him reconsider their relationship.

OK! NEWS KIM KARDASHIAN SHOWS & TELLS GIRLS TO "EMBRACE YOUR CURVES"

But is there more trouble ahead?

Reggie isn't the only person in Kim's sphere who has something to say about her dates with the world-class soccer star.

According to pals, Kim's longtime frenemy, Paris Hilton — who was briefly linked with Cristiano in 2009 — is less than happy about the budding romance.