Since D.J. picked neither Steve or Matt it has been confirmed both will get new girlfriends. Steve will get a D.J. "Clone" named JD.
D.J. Tanner-Fuller (Best Friend)
Steve Hale is D.J.'s first real relationship. Steve tells D.J. about his true feelings in the episode "Lovers and Other Tanners". They had their first "date" in the episode "Sisters in Crime", where they were supposed to watch a more adult movie, but instead, since Michelle and Stephanie were there, they went to a child movie instead. Steve and D.J. met again when they saw each other on the plane when they were both going to Spain, and they became a couple after they came back.
When the Tanner family went to Disney World, Steve is forced to remain behind. However, he misses her so much that Steve ends up visiting D.J. at Disney World in the episode "The House Meets the Mouse" (Part 2). This proves that he loves D.J. so much that he can't stand being apart from her, so that's a big stepping stone in their relationship.
In the episode "The Perfect Couple", Joey asks Steve and D.J. to be the dating couple in the game show he is hosting, The Perfect Couple. They agree, but D.J. soon starts to question saying yes. She worries about not knowing each other, which she is right about after they play the game show. But Steve tells her that every time he learns something new about D.J. is like Christmas.
Steve told D.J. about his being accepted to a college in Florida. He didn't understand why D.J. was sad about that, but the reason was because she was worried about what would happen to their relationship. In the episode A Very Tanner Christmas, Steve gave her a sweater from that college, but that only made her more upset. In the end, he decided to stay with D.J. and go to a junior college to improve his grades.
When Steve is about to go to college, his relationship with D.J. slowly becomes weaker, resulting in their breakup in the episode "Love on the Rocks". On the series finale, "Michelle Rides Again (Part 2)". Steve makes a surprise visit to be D.J.'s date to her senior prom, and to be her escort.
When they reunite 29 years later, Steve still has feelings for D.J. and says that he will hold out on waiting for her whenever she is ready to date again after the death of her husband. However, he finds out at a Giants game that she has feelings for her co-worker Matt Harmon, which culminates in a rivalry between the two for D.J.'s affection. Both men go on a date with her to compete for her affections but in the episode "Love Is In The Air", she ultimately chooses neither man as she believes her complicated feelings are proof enough that she's not ready to date again.
Over the summer, Steve begins dating a new girl named C.J. who appears to mirror D.J. and her mannerisms in every way. Though he does seem to still have some feelings for D.J. when he appears jealous upon finding out Matt is dating her, he remains faithful to his love for C.J. and agrees to be best friends with D.J. no matter what happens in their lives.
Stephanie Tanner (Friend)
Stephanie, like Danny, makes fun of how much Steve eats at their house.
Along with D.J., Steve is mad at Stephanie for breaking into his apartment in the episode "The Prying Game". Luckily, they both get over it in the end.
Matt Harmon (Husband)
Steve kisses Kimmy in D.J.'s nightmare in the episode "The Test". Before that, he had assured D.J. that he would still love her, even if the only thing she got right on the test was her name. In the episode "The Last Dance", Steve is the one who tells Kimmy that D.J.'s grandpa, Papouli, passed away. (It is presumed that if he hadn't told Kimmy that, she would not have come over to D.J.'s house, and they would not have apologized to each other.)
As mentioned above, Steve begins to date C.J. over the summer after D.J. turns down both Matt and Steve. First dating her due to how much she reminded him of D.J., he eventually falls in love with C.J. and proposes to her in the episode "Happy New Year, Baby", though he has to do this with D.J. as a translator since he becomes nervous and C.J. happily accepts.