"...You leave me no alternative. I have a letter written already. Here it is. You see the address. If you don't help me, I must send it. If you don't help me, I will send it. You know what the result will be. But you are going to help me. It is impossible for you to refuse now. I tried to spare you. You will do me the justice to admit that. You were stern, harsh, offensive. You treated me as no man has ever dared to treat me--no living man, at any rate. I bore it all. Now it is for me to dictate terms."

I was just wondering what others made of this and what people think happened between Dorian and Alan Campbell.

My guess was perhaps they were lovers, and Alan Campbell called off their relationship abruptly. I find it interesting that while it is hinted at, it's never actually said what happened, and it really bothers me that I don't know!