Well Arthur missed the conversation about Eames and schadenfreude, so he'll never know. His delight in seeing Arthur fail to get any in such an (he assumes) embarrassing way for everyone is multi-faceted and he's not going to explain any of it.

He is, however, not interested in this conversation and takes a moment to inspect his nails out of boredom.

"Well it's nice to see you both being adults about this."