WHy do I have thoughts of the same person all the time?

Could be something you are avoiding or searching for.

What does this person mean to you?

There really isn't enough info here to give a good answer. If you can give more info, we can help you more.

Who is this person?

What does s/he mean to you?

etc.

WHy do I have thoughts of the same person all the time?
Are you in love with the person.

You don't have to have these thoughts if you don't want them. If you are holding onto them it's probably because you enjoy them. If not begin right now to change what you are thinking.

The simplest way I know of is to chose some new music for yourself - not something that reminds you of anyone or anything - something completely different.

Go listen to it and when thoughts of this person come into your head, simply say NO THANK YOU.

It won't work over night and it will depend on how determined you are to change what you are thinking. But it will work if you want it to.

On the other hand…… Maybe you just fancy him and can't stop thinking about him - perfectly normal.