Story
When Katie first saw Kyle, they were on the rooftop of Katie's, now both Katie and Kyle's, apartment building, attending a Kentucky Derby party hosted by Heidi and Arjun (in the wedding party). Kyle showed up just a little after Katie did and caught Katie's eye... then offered to refill Katie's drink and Etta's drink too (a very sweet gesture). Katie had taken a law school exam that day and coincidentally was in desperate need of a refill. Later in the afternoon, they chatted more and spent time connecting over having both lived in Kentucky even though Katie only lived there briefly.
Even later on in the evening, the party moved downstairs in order to (at least pretend to) watch the most exciting minute in sports (which nearly no one could remember who won the Derby later and where a technicality led to a different winner being declared later). Kyle knew he was interested when Katie made a silly face at him (unthinkable to anyone who knows Katie), and Kyle thought his chances were pretty good in light of the gesture. Kyle asked for Katie's number shortly thereafter, and the rest is history.