Zacharias was sure that the appropriate response here was to go with that instinct that told him not to look. It certainly would be safer and he really wasn't one to go looking for trouble. But at the moment, the other option was to yell at Anthony or just give it up and return to the office and admit dinner defeat.
"But why?" Rather than focus on the alley, which he couldn't seem to do, he was watching the people interact, or decidedly not interact with it, and it sort of bothered him. Especially the part where he sort of wanted to know what was going on. "If it's just a couple having at it in the alley, that would be a strong don't-notice spell there."
Curiosity could be a horrible sort of thing and this instance caught his. He might not have been looking to be a hero, but even as the spell was directing him to let it go, he just couldn't.