This is the last time that I will send a message to you because I know you never think about it, that you'll come back to me, or you may have a new relationship.
This is the last time I will send you a message. Because I know that you never thought about it that you would come back to me. Or you may have a new relationship now.
This is the last time I will send message to you. Because I know you never think about that you will come back to me. Or you may have a new relationship.