You and Percy have been dating for about a year.

You knew that annabeth liked him. And you noticed her trying to separate you. But every time you said that, Percy said she didn't like him.

So, you wanted to run a test.

You sent Percy to go find annabeth, and tell her you broke up, even though you didn't.

If she didn't try to get with him, she doesnt like him.

But if she does try to kiss him or something, then she obviously does like him.

You were standing behind a tree, listening to Percy and Annabeth talk. He barely finished saying you broke up before annabeth practically jumped on him, kissing him.