Sora and Yolei don't know each other that well, but they seem to get along very well. Yolei's first Digiegg, the Digi-Egg of Love, has the same Crest as Sora, showing the two could be close. They were even partners during the trip around the world when they went to Russia.
Yolei looks to Mimi as a role model or an older sister, stating in Mimi's first 02 appearence that she wanted to be just like her. She also shows confusion at Mimi's actions when they are going up against Digitamamon, until she realizes what Mimi is doing and so she gains the Digi-egg of Sincerity, Mimi's crest egg.
T.K. lives in the same apartment building as Yolei.
Yolei is Kari's DNA Digivolution partner. This may be because Kari and Yolei are polar opposites: Kari is quiet and calm whereas Yolei is rash and talkative. Despite this, the two share a close friendship and seem to be very close.
Cody and Yolei have lived in the same apartment building for a while prior to Adventure 02, and thus she knows him very well.
Yolei exhibits a crush on Ken when she sees him as a genius boy, but eventually becomes disgusted by him when she finds he is the Digimon Emperor.
After Ken finds his normal self again, Yolei is initially nervous to trust him, especially when the DigiDestined watch him kill Control Spire Digimon and believe he is killing normal Digimon. However, once she realizes what he is doing, she trusts him and accepts him as a member of the team, eventually becoming supportive of him as well as reviving her crush on him.
Yolei and Ken are married at the end of Adventure 02.