Imagine person A of your OTP being too nervous / scared to ask person B out to prom / any other event. They ask their friend if they can practice asking with them.
While they're practicing, person B happens to drop by with the intention of asking person A out and overhears the conversation, thinking that person A is now going with their friend.
Person B then asks someone else to accompany them to said event so they won't have to go alone, of which person A hears. Both show up with different dates but are incredibly unhappy as they're there.
Whether the issue can be solved and how is up to you.