“I know. I offered her an orange drink and the way she jumped when she said no, you’d think I’d thrown it in her face"
"So he's the reason"
Mrs. Sakkaro dramatically declines when offered a drink by Lillian. This can be considered situational irony, because Mrs. Sakkaro is not acting the way you would've expected.
As Lillian and George are walking a path to the park with the Sakkaros, George jokingly says "So he's the reason," after seeing how "dark and handsome" the Sakkaros were. This can be consdered verbal irony because although he said that line, he didn't actually mean that, Mr. Sakkaro's image was the reason, he was just joking around.
The last name Sakkaro can mean sugar, referring to the last scene where the Sakkaros melt like sugar. This can be considered to be dramatic irony because this is a key component that the reader can figure out, that the Wrights are unaware of.