When she decides that she wanted to apologize to Yamcha, she sees what looks like Yamcha holding another woman, however, Yamcha was actually trying to disarm a scimitar from.
She thought that he was killed but Master Roshi during the finals and cried but was relieved when he turned out to be okay.
Basically, the whole reason why the Shadow Dragons even came into existence was because of the fact that the Dragon Balls were constantly being abused for wishes.
For instance, Bulma spent large amounts of time with Whis, at one point, showing him all sorts of new foods and cultures because she wanted to form a bond with him.
Bulma's companionship with Goku also extends to his family, being a good friend of Chi-Chis and showing a great deal of warmness to his sons Gohan and Goten, even after the former grows up.
One of Bulma's most interesting relationships is her friendship with Goku, having known the Saiyan for the majority of his life and becoming his first, and one of his closest, friends.
It's also implied that she'd done this a few times before.