As one of Ranma's fianceés, Ukyo does harbour romantic feelings towards him. This wasn't always the case, since as children Ukyo and her father saw Ranma as nothing more than a freeloading nuisance which Ukyo would constantly try to defeat, but always fail (whilst Ranma viewed Ukyo simply as nothing more than a friend). Despite this, Ukyo does begin to have feelings for Ranma, even going as far if he'll take care of her if the Sauce of Ten Years she made turns out good, a request which Ranma agrees to. Presumably a short time after this, Ukyos' father, seeing no other way for his family business to continue, asked Genma for their children to become engaged. Initially Genma tries to explain that Ranma already has a fiancé (Akane Tendo), but hearing that Ukyo's father would be willing to throw in his Okonomiyaki cart as a dowry, Genma's greedy nature takes over and he agrees to the engagement. Unfortunately in Genma's haste he left Ukyo behind.
Through the abandonment from the Saotomes coupled with teasing from the other local young girls, Ukyo's feelings towards Ranma turn towards hatred and revenge, prompting her to vow to become the greatest Okonomiyaki chef in order to hone her skills and beat Ranma once and for all. These feelings continue until Ukyo finally meets Ranma again ten years later in Furinkan. However, after Ranma repairs Ukyo's giant Spatula he comments on how cute she is which embarrasses Ukyo greatly. Shortly after hearing this as well as observing Ranma's rather "rocky" relationship with Akane, Ukyo begins seeing herself as having a shot with Ranma and her feelings towards him increase.
After an unsuccessful attempt of exploiting Ryoga's infatuation towards Akane as a way for her to get closer to Ranma (which was partial spoiled by Ranma himself), Ukyo learns of Ranma's Jusenkyo curse, but quickly accepts it and even initially views it more like play-thing rather than any sort of curse. Ukyo even used Ranma's curse as a way for her to rid herself of a previous affiliation who developed romantic feelings for her, Tsubasa Kurenai.
For this point on Ranma and Ukyo's relationship remains relatively unchanged, with Ukyo continuing to try and get Ranma to be only her fianceé whilst Ranma continued to view Ukyo as nothing more than a good friend. However, when Ukyo unearths her Sauce of Ten Years and discovers how horrible it is (through Ranma being impatient and ruining the recipe shortly after the Sauce was made), Ranma could not bring himself to hurt Ukyo's feelings so he continually lies and claims the sauce tastes fine. Ukyo, meanwhile, was disgraced with her sauce and vowed to give up on being an Okonomiyaki chef in favour of becoming a dutiful wife for Ranma. Eventually, Ukyo decided that she must find a way to be great Okonomiyaki chef and a wife, so went back to Okonomiyaki Ucchan's to continue her training.
A brief moment occurs in Love's Counterstrike (and its OVA counterpart) when Ranma asks Ukyo if she loves him. After a moment she says that she does love him, then slaps him into a tree and runs away embarrassed.
In Ukyo's Skirt! The Great Girly-Girl Gambit, Ukyo began wondering how she can appear more feminine towards Ranma. She eventually decided to start wearing the female Furinkan High School uniform along with more skirts. When word of this reaches out, Ranma's other fiancés become jealous at Ranma suddenly spending more time with Ukyo and a cooking contest is devised to see who Ranma's true fiancé is. Unfortunately the competition gets out of hand and Ukyo grudgingly realises she should've left things like they were before, so decides to put her dresses back into her closet and returns to wearing more masculine clothing.