Dear …
I recently started seeing someone locally and __(he/she)__ has been getting all my attention these last few days.
To be honest with you, __(Name)__, I have tried long distance relationships before and I am just not good at them. So in all fairness to you, I think it would be best to leave this be. It was fun chatting with you, but the distance just gets in the way.
Good luck to you in your search, __(Name)__ I hope you find the girl of your dreams.
Sincerely,