The 43-year-old singer/actress has previously been married to Ojani Noa, Chris Judd and Marc Anthony and has been dating back-up dancer Smart for almost two years.
A source told OK! Magazine: "She calls him 'love of my life.' She believes it, she thinks he's the one she's been searching for all these years.
"He may be younger, but she says he is the most secure man she has ever met. He constantly inspires her and lifts her up.
"Jennifer knows a lot of people in her life don't approve of her marrying Casper, but she's stopped caring. She wants to be his wife."
Lopez's twins, Maximilian David and Emme Maribel are said to be "huge" fans of Casper. The source continued: "Casper is devoted to her kids. He is a second father to them.
"Jennifer says he's much more playful and present than their own dad a lot of the time."
Best of luck, J Lo!
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