Media attention has focused on her personal life. She has had high-profile relationships with Ojani Noa, Cris Judd, Sean Combs, Ben Affleck, and Marc Anthony. Starting 1984, when Lopez was 15 and in High school, she started dating David Cruz. They split in 1994, and still enjoys a close relationship with him ten years after they split, Lopez said in 2004: "He's a friend and he probably knows me better than anyone else".

Lopez's first marriage was to Cuban-born Ojani Noa on February 22, 1997. Lopez met Noa while he worked as a waiter at a Miami restaurant. They divorced in January 1998. Lopez later employed Noa as the manager of her Pasadena restaurant Madre's in April 2002, but he was fired in October 2002. After Noa sued Lopez over the termination, they drew up a confidentiality agreement. In April 2006, Lopez sued to prevent her ex-husband, Noa, from publishing a book containing personal details about their short marriage, contending it violated their confidentiality agreement. In August 2007, a court-appointed arbitrator issued a permanent injunction forbidding Ojani Noa from "criticizing, denigrating, casting in a negative light or otherwise disparaging" Jennifer Lopez. She was awarded $545,000 in compensatory damages, which included nearly $300,000 in legal fees and almost $48,000 in arbitration costs. Noa was also ordered to hand over all copies of materials related to the book to Lopez or her attorney.

Lopez next had a two-and-a-half-year relationship with hip-hop mogul Sean Combs. On December 27, 1999, Lopez and Combs were at Club New York, a midtown Manhattan nightclub, when gunfire erupted between Combs' entourage and another group. Lopez and Combs were being driven away from the scene when they were chased and stopped by the police. A gun was found in the front seat of their vehicle. Combs was charged with felony gun possession. Stress over Combs' trial and pursuit by the press multiplied their problems, and Lopez terminated her involvement with Combs one year later. Durng a related civil suit in 2008, the plaintiff's lawyer said Lopez had ?nothing to contribute to the case?.

Her second marriage was to her former backup dancer, Cris Judd. She met Judd while filming the music video for her single "Love Don't Cost a Thing." The two were married on September 29, 2001, at a home in a Los Angeles suburb. Their marriage effectively ended in June 2002, when Lopez began publicly dating Ben Affleck. They were officially divorced in January 2003.

Following her divorce, Lopez began dating actor Ben Affleck. Her relationship with actor Affleck was highly publicized, with the media dubbing the couple "Bennifer." Lopez announced her engagement to Affleck in November 2002, after Affleck gave her a six-carat pink diamond ring worth a reported $1.2 million. Lopez promised interviewers that Affleck was indeed "the one", and that they would soon have a family. The marriage, planned for September 14, 2003 in Santa Barbara, California, was called off just hours before the event. Their relationship was parodied on the South Park episode "Fat Butt and Pancake Head", which aired on April 16, 2003. Affleck has since married actress Jennifer Garner on July 1, 2005 and they have 2 daughters, Violet, born on December 1, 2005 and Seraphina, born on January 6, 2009. In 2003 Jennifer Lopez and Ben Affleck acted together in the film "Gigli" and in the 2004 film "Jersey Girl".

Lopez and Marc Anthony at the 2006 Time 100 gala event. Shortly after her break-up with Affleck, Lopez was seen with singer Marc Anthony, a longtime friend with whom she had worked in music videos. They had briefly dated in the late 1990s, before his first marriage and her second. Lopez and Anthony were recording a duet together in early 2004, for Lopez's then-upcoming film Shall We Dance?. In October 2003, Anthony became separated, for the second time, from his first wife, former Miss Universe Dayanara Torres, with whom he has two children. Torres filed for divorce three months later. Lopez and Anthony married in a quiet home wedding on June 5, 2004, four days after his divorce from Torres was final. Their ceremony was private and unpublicized. In attendance were an estimated forty close relatives and friends. On the morning of the wedding, however, the media was tipped off and circled her backyard in helicopters. Photographs, alerting the rest of the world, soon followed. Reports fueled rumors that Lopez was pregnant but this was not the case. Lopez's guests had been invited to an "afternoon party" at Lopez's house and had not been made aware that they were actually going to her wedding. The couple had planned not to publicize their marriage early on, allowing more privacy and time together in an otherwise intrusive environment. Days after the wedding, Anthony refused to comment on their marriage during interviews which were scheduled earlier to promote a new album "Amar Sin Mentiras" (To Love Without Lies). In February 2005, Lopez confirmed the marriage, and added that "everyone knows. It's not a secret". A few months later, Anthony's daughter, Ariana, appeared at the end of Lopez's music video "Get Right" as her little sister. Regarding his marriage and family life, Anthony maintains a private and sometimes defensive stance with the media, which has influenced Lopez to set some boundaries with interviewers. On December 29, 2008, Daily News reported that Lopez and Anthony planned to announce their divorce on Valentine's Day. This allegation was put to rest by her publicist stating that "There is no merit to the article".