You really shouldn’t lie about your age on the internet. If you are uncomfortable saying how old you are, then you should just not say at all instead of lying. When you lie, it can mislead other people and if they do find out that you lied, they can get hurt. You should just tell him in a straight forward way. Don’t beat around the bush. Just think, if he returns your feelings and you two are prepared to have a long distance relationship, he will be very hurt that you lied to him. Even if he has a sister the same age as you, you shouldn’t conceal your age if you truly value his friendship or if you want to think about a relationship. A relationship built on a lie will generally die faster than one built on honesty. And remember, long distance relationships, especially cross-continent ones, are difficult to maintain and require a lot more communication than local ones. You can’t afford to lie to him if you want to consider long distance.