Two characters like each other. Instead of talking for thirty seconds, they spend 300 pages in a spiral of jealousy, misheard conversations, and petty pride. Why it fails: It makes your characters look immature, not tragic. A simple conversation would solve everything.
Your protagonist sees the love interest across a crowded room. Time stops. They think, “They are the most beautiful creature I have ever seen.” By page ten, they would die for them. Why it fails: It mistakes attraction for connection. Readers want to see the reason for the love, not just the result.
If the answer is yes, your readers won’t just ship it. They’ll live inside it.