Everyone has ex - relationships. We build our experiences through failed relationships, we jump in the romances which will not end well. Maybe we know from the beginning there is no future, but we are tempted. Then we make an attempt and it fails.
Every past relationship is not a bitter experience. After we froze our feelings and time pass, we could modify our romance to friendship. Yes, that person is still in our life, just with a different role. We are not kissing and cuddling anymore, we just want to be there as support.
There is no problem if we have an agreement. You know where is the line. I will talk to you and you have my loyalty, but it doesn't mean that I will jump in your bed when you get horny. If I was in your bed once, it doesn't mean I am obliged to do this forever.
The problem appears when your ex uses your friendship like an intro in sex adventure. So, I am listening to you, and now I will hug you and you will be mine again. You will be in my bed because it is not the first time.
There is a reason why someone is your ex-love.
Your relationship failed because of a big expectation.
Someone of you cheated.
Your ex never had time for you.
Your ex left you because of another person.
Your ex ignored your wishes.
When something was good in your past relationship, your ex could fake friendship and stick to a reason which connected you.
You are weak on him because he made you smile.
He was a great lover.
He knew your secrets.
He understood your bad mood or a hot temper.
Every relationship taught us, but it once was over and years passed, it is a wrong way to get back.
Maybe you are not the same person now.
You progressed and he is still standing in one place.
His ego is so big that he thinks you will wait for him forever.
He could not find a suitable match so he came back to you.
Sometimes, friendship with an ex is not possible, because every time you talk to him, he wants to use this situation to make intimacy. This chapter is over for you, so don't hesitate to say no. If only silence can prevent you to be used again, use ignorance. Words which are not said are very powerful. You save your time and show your attitude in a silent way.
Another thing is if you want to set a fire between you and him again. This depends on you, but don't let someone drag you in the illusion which happened before.