The situation is as follows: Someone your character never really noticed - let alone had feelings for - before turns out to be secretly in love with them. How they handle decisions in their love life, and what people they want to connect with can say a lot about a character. What would they do in this case? Would they give the person a shot? Shut them down gently? Ignore it and hope they move on? Write a scene, or just describe how they would react in hypotheticals; it's up to you!