Answer:
coincidence
Step-by-step explanation:
irony:
(In an ironic phrase, one thing is said, while another thing is meant. For example, if it were a cold, rainy gray day, you might say, “What a beautiful day!”)
and there are many types of irony. eg. verbal irony, sarcasm, situational irony (when someone says something ironic accidentally, without intent),...
coincidence:
(A coincidence is something that's not planned or arranged but seems like it is. Technically, a coincidence is an occurrence of events that happen at the same time by total accident––like you and a kid from your class at school both visit the Grand Canyon on the same day.)
so by that logic, the most beautiful girl living next to the most handsome boy is a coincidence.