"We're solid." (cue affair)
"I can't stop thinking about you." (during affair)
"I'm in over my head" (Robbie from ED calls for help in the bath, or affair progressing)
"How could you?!" (affair rumbled)
"I promised myself I wouldn't cry" (said at funeral of one of those involved in affair)
"He/she had the whole world in front of him/her" (at every single funeral)
"We can get past this" (post-affair, pre-awful event).
My personal pet hate is "I promised myself I wasn't going to cry" though.