Guy and Karina are never formally introduced. It is presumed they were either introduced by their parents, Kendra, Andre, Kline or May, at a young agie or that they met while in school as children. They did not have much attention in the original series until near the end. When Kline and Karina return to Ribbon Heights years after the death of Karina's mother, May Haller. When she returns ahd and Guy immediately begin to date, now being young adults. When Guy expresses his interst to propose to Karina his parents voice their objection. At Kline's wedding to Roberta, Karina dumps him when she hears he was going to aks her to marry him, for an un-known reason.
Sometime later Guy and Karina reconcile and actually do become engaged. Though their parents and Roberta are hesitant they come to grips with their union and begin planning for the wedding. As the wedding approaches Kline and Roberta announce their plans to move far away and it is evealed that Guy and Karina will be going with them. Kendra becomes saddened and does her best to convince them to stay in Ribbon Heights. They refuse to relent and Kendra and Andre deal with it. Guy and Karina are then wed in the series finale and then move away with Kline and Roberta someplace far away.
In the spin-pff, set ten years later, Guy and Karina return to Ribbon Heights and decide to remain there from now on. However, they are adults and have no children. Guy's mother, Kendra, quickly begins to pester them to have some kids before it is too late. Children seem to be an emotional topic for the two, meaning they are hiding something. After some probing it is revealed that Guy and Karina had adopted a son, Terry, who was taken away from them when his biological mother wanted him back. After some convincing Guy and Karina decide to have a child, biologically and Karina quickly becomes pregnant.
After some time she gives birth to a daughter, Myra. They new family then sets out on a vacation and upon their return they discover that someone has been living in their home while they were gone, Terry. Their former adopted son, who is know a teenager informs them that his mother has died and he would like it if they would adopt him again. Though they were hurt in the past, Guy and Karina instantly accept the offer and Terry becomes part of their family. However, Kendra worries that Terry will hurt her son's family again and warns Terry. Terry then tells Guy who shuts Kendra out of his life.
Thus causes a strain on his and Karina's relationship as she even feels it is a bit harsh. After some realization Guy comes around and he and his mother reconcile. Guy and Karina then face the troubles of raising a teenager when Terry begins sneaking out to see his girlfriend, Cari Chalk. They later talk to Gregg Chalk and tell him to get tough and though he is shocked by their harsh judgement he agrees to do so. Guy and Karina then happily decide that they would like to have another baby and attempt to become pregnant again. When Karina fails to become pregnant she then discovers that she can no longer have children and breaks down.
Karina then falls into a deep, deep depression. Guy does his best to get Karina out of her funk, but to no avail. He later tells her that is she refuses to get over the news then he will have no choice but to divorce her. Wendy Jule then goes to speak to Karina. She tells her that she is the daughter of May and that May was one of the strongest women Wendy ever knew and that Karina can beat this, she just has to try. Wendy's words reach Karina just not the way Guy had hoped. Karina then tells Guy that they should have "flings" to enhance their own romance. Guy shuts the idea down, but Karina intends to pursue the action.
Guy then becomes worried that Karina will cheat and she does. He catches her in the act with Henri Deux, the ex-boyfriend of Neve Lord-Chalk and Adia Faison. After this he confronts her and tells her he wants to seperate and Karina gladly leaves. Divorce proceeding then begin but everyone in town knows that Guy and Karina truly love each other and try to repair the relationship. Kline and Roberta are then called and come to town as fast as they can. After speaking to Karina, she breaks down and tells them how she can't have any kids. She and Guy then reconcile and after the Pierre du Gard mystery is solved and he is killed, they decide to adopt his daughter, Eleanora.
When Terry grows up and moves out, he then moves out of town and Guy and Karina decide they want to be with their son so they pack up Myra and Eleanora and move along with their son after the wedding of Regan and Gal. They briefly return after Kendra dies and help to get her affairs in order. Their marriage remans stabelized from here on out. Guy confronts his brother-in-law about his affair and Karina comforts a pregnant Neve. They then later leave town, but it is revealed that Terry and Cari have married. Guy and Karina are last seen at Charis Onassiser Siddle Templeton Saunter Hallworthy Saunter's final wedding. They age into elders and share a romantic dance.