How should I reply to this text message? To return or not to return? What should I say if you call?

Let’s see what kind of character he is.

Be cheerful, you can just tell him ‘I don’t have feelings for you! ’ ‘You’re not my type’ and so on. If he says it will happen after a long time of dating, just say you don't know... and ask for some more time to observe, and make it clear that if you don't feel it anymore, you can't continue... He understands!

If you are introverted, try to become more indifferent to him and let him retreat. Maybe he mistakenly thinks that you can accept it because you always reply to your letters and answer your words...

(With the focus on not hurting other people’s dignity, and also showing that you are helpless, If necessary, just say 'I really can't like you')