You try not to get involved in people's personal problems. This, if he was honest with himself, in his line of work was extremely hard to do. Because nine times out of ten, he was there because of people's personal problems. He was gainfully employed because of other's people's problems. However, most of the time, he's able to keep the reason why he's involved in other people's lives separate from whatever soap opera these people chose themselves to be in outside of threats from legitimately crazy people.
When you are employed to follow someone around, more often than not, you manage to piece together what is going on in their lives. You sign your own life away first – the standard Non-Disclosure Agreement is half an inch thick anymore – but for some of his collogues, knowing this much about 'the beautiful people' is what makes these jobs worth considering. How the other half lives. The vast amount of guys in his line of work has nothing to be at home for. They have bills, broken relationships, people they never want to see again, copious amounts of PTSD and the easiest way to forget all of that is to work. Work for some of the most dysfunctional people that roam the earth.
Lonny Church can't help but smile when he hears the phone calls Will McAvoy makes to close the Executive Dining Room. Because Lonny knows that Mackenzie never takes a lunch. Will never takes a lunch. Will asks for yellow flowers on the tables because 'she' likes yellow flowers. He arranges for mimosa to be ready by the kitchen – no pulp. The one that makes Lonny stifle a grin is the request for a piano player – specifically if that piano player knows how to play Burt Bacharach songs. That took three phone calls alone. These are things that don't make sense to Lonny about Mackenzie, but he understands enough to know that as long as Will knows these things, then Will's making an effort. Maybe Will can finally put that ring from Tiffany's to use.
So Lonny tries not to smile when Will starts to ask him for a favor. That if he could bring someone to the Executive Dining Room by the freight elevator. Lonny is almost tripping over himself to say yes until Will tells him who he's to bring. Nina Howard. Lonny flashes anger but composes himself quickly so Will doesn't really notice and tells him gently in his best diplomatic voice no, because he has an appointment. However, his backup, a former New York City Police Detective is more than able to handle the job. Lonny can see Will's eyebrows knit together for a moment, but he takes the rebuff in stride.
Lonny is professional enough not to hit Will McAvoy in the back of the head, but he's having a hard time talking to Will since he formulated this plan. Lonny likes Mackenzie, he likes her a lot, and he decides that he likes her enough not to see her be hurt or even know that's she's going to be hurt. For all of Will's lecturing about the mission to civilize, he's nothing more than an ass to Lonny now. So, it's a subtle change, but he starts to alter the schedule so he no longer has to deal with Will McAvoy in his waking hours. It's much easier to watch an apartment instead of watching this man make mistakes.