Hi Delljoy! I agree with Rohag and encourage you to seek as much information on this site as you can and when he comes back, because he seems to have built a patter of infatuation and rejection, perhaps you can have a quiet talk with him to address these issues you've noticed. There are ways to do this in a non-confrontational manner, but I fear if you don't look into it, you're only going to remain on this rollercoaster, and trust me, it's not a fun ride.

Please take care of yourself, first and your mental health. If you do want to help him, then the only way you can is to be as sure as you can be, that you are as strong within as you are without. Good luck, and keep posting. We are all good listeners here, and probably many of us (myself included) have traveled down the road you have encountered and hopefully can be of some help to you.