These are the relationships Alicia has with characters in the show.
Boyster and Alicia had both always been deeply in love with each other, but Alicia always seemed to have had an easier time hiding her emotions (in other words, smoother) when Boyster was around. During Season 1 and 2, neither were capable of expressing it, even though they were both aware of the other's affection. So far, Alicia has kissed Boyster on the cheek three times (in "The Necklace", "The End," and "The Misunderstandings"); in addition, they attempted to kiss on the lips twice - once in "The Pressure," and another in "The Party." Both attempts failed as in the former, Ozzy chopped down the treehouse that the kiss was taking place in, and in the resulting confusion, Boyster kisses Rafik on the lips in "The Pressure". In the latter, the moment was ruined by Mr. Likowski honking his car horn loudly and interrupted the moment, so Gumball instead said to Penny that he loves her in "The Party," causing her to blush. Also in the episode "The Meddler," Penny and Gumball are shown to both love each other with Gumball accidentally saying that he doesn't love Alicia which causes her to turn away crying. Later in the episode, Boyster fails the cheer leading tryouts and sacrifices his dignity for Penny, and in return, Penny forgives him and concludes that Gumball likes her after all. In "The Date," she had invited Boyster to her pet Mr. Cuddles' funeral, but Boyster mistakes it for a date and ends up embarrassing himself and losing Alicia's Parents' respect for him. In the end, Boyster had found Mr. Cuddles in the bathroom, gaining back her, and her parents' respect. An example of her affection for Gumball that isn't important was in "The Mystery," when she and Darwin cannot be spotted chasing after him angrily like the rest of the students. Despite this however in a rather notable out of character moment she along with several other students laughed at Boyster when he was naked in "The Dress."
In Season 2, Gumball and Penny's relationship was explored further. In "The Knights," Gumball and Tobias both compete for Mr. Fitzgerald's permission to work on a medieval times project with Penny. Near the end of the episode, Tobias and Gumball "duel" for Penny's affection, and Tobias pushes her into the road. At the last minute, Gumball pushes Penny out of the way of her father's car, saving her life, and winning his respect once again. However, Mr. Fitzgerald crashes into The Wattersons' house, angering the family and thus reversing the situation for himself. Again in "The Flower," Gumball competes for Penny out of jealousy of Leslie. His envy personifies itself into Gumball's soul, causing him to use very drastic measures to get rid of Leslie. Concerned for Leslie's well being (and Gumball's sanity), Penny, Darwin and Leslie resort to Carrie to exorcise Jealousy. After a lengthy cycle of Jealousy traveling for person to person, Gumball was freed of the entity. Soon afterward, Jealousy takes over Penny when Carrie gives Gumball a playful punch in the arm.