The last few moments of [REC] 3: Génesis, Koldo and Clara just barely made it out live until Koldo's grandfather bite Clara's hand. The reason why he wasn't affected by the priest's words because he was deaf and could not a anything from him. Clara was willing to sacrifice her arm to stop the infection by having Koldo sever it, but unfortunately it didn't stop her from becoming one of them. Crossing into Nightmare Fuel and Heartwarming territory, rather than abandoning his now demonic zombie wife, Koldo carried Clara out the gates in his arms and they had one last kiss... and then Clara bit off his tongue, turning him into a demonic zombie. After the couple was gunned down, with the bit of humanity and life they had left, they held each other hand just before they died.
Also the fact that they could have had family together went out the window thanks to The Virus and Koldo's deaf grandfather.