Answer:
You can lose sight of your priorities.
You can take little things too seriously.
If he/she knew he/she may use you.
You will feel more hurt by he/she's insults.
If you told someone that someone could tell everyone.
If someone hears you mentioning the word crush, they will start rumours about you.
He could hate you.
He could like someone else.
If everyone found out, you would get teased.
He might get teased or bullied because of it.
He might make fun about you.
You will be too caught up trying to make him like you.
You could accidentally embarrass him.
You will be blind to his imperfections.
You will lose focus on yourself and the beauty within.
