After briefly dating Nikhil Sharma (Rik Makarem), Katie becomes interested in Declan Macey (Jason Merrells) and his ex-wife, Ella Hart (Corrinne Wicks), tries to warn her off but Katie and Declan begin dating regardless. When Declan's daughter, Mia (Sapphire Elia), dies in a car crash, he reveals that he was not her biological father and Katie supports him through his grief. Declan proposes twice to Katie but she turns him down on both occasions. However, she does move in with him at Home Farm and they are happy together until Declan's half-sister, Megan (Gaynor Faye), visits and takes an immediate dislike to Katie. Megan helps Declan organise a music festival and Katie works hard to convince Megan that she is with Declan because she loves him, and is not after his money as Megan believes. Megan tells Katie about Declan's money troubles being the reason he had contacted her and asked for financial backing with the festival, causing them to argue. Katie leaves briefly but Megan apologises and asks her to return. Katie supports Megan when she reveals that she gave her son, Robbie Lawson (Jamie Shelton) up for adoption when she was younger. Declan finds Robbie and he moves into Home Farm as well. Robbie flirts with Katie and tries to persuade her to leave Declan for him but when she rejects him, Robbie starts making her feel uncomfortable. In retaliation, as Declan refuses to ask him to leave, she manipulates a situation in which Robbie tries to kiss her and uses the CCTV to film him attacking her, wanting to expose his true colours. Declan believes her but Megan suspects the truth and blackmails Declan into allowing Robbie to stay, making Katie move out. However, Declan apologises and he proposes again. This time Katie accepts, much to Robbie and Megan's disapproval, and Declan plans to keep all the festival profits for himself and Katie agrees to help him. Megan interrupts Katie and Declan's wedding when Robbie tells her what has they had done. However, she leaves and the couple marry but at the reception, Megan pushes Katie's face into the wedding cake.