Swing- when Kathleen went missing, Kathy and Eli rushed to see Elliot at the squad. When Kathleen went to jail (thanks to Elliot turning in evidence) Kathy slapped Elliot in court and he knew he was in the doghouse.
Lunacy- Elliot told Dickie he gave up his dream when he realized that he had what he already had: Kathy with Maureen on the way
Wildlife- Kathy attempted to leave Elliot again when he failed to notify her about going undercover. Olivia reassured her and caved in. Olivia checked in on Elliot, who no longer had his undercover cell phone and wallet; Olivia gave him hers so Don can keep in touch. Elliot wanted Kathy to know too. He knew she was mad. Later Eli's crying woke up Kathy who attempted to get up for him but Elliot grabbed her arm. He's got Eli, despite being shot twice.