He had been seeing Jenna D'Sora, but she broke up with him in 2367, due to his never having enough time for her and generally not making an effort to improve their relationship. She even objected to the noise he made when eating soup.
Jenna bumped into Jeff aboard the Enterprise at least twice, a week apart, the most recent time being in the turbolift. The first time was difficult for her emotionally; the second time (six weeks after the breakup), he asked her to dinner. Jenna told him she'd think about it. When she told Data this, he listed her the reasons she'd broken up with Jeff for the third time, and asked her if she wished him to stop reminding her.
It was their breakup which inspired Data to study the dissolution of relationships as a sub-discipline of Human intimacy. Later, when Data informed Geordi La Forge that Jenna seemed interested in him, LaForge was unaware that D'Sora had broken up with Arton. (TNG: "In Theory")