when i first started out online, i played with a dom who i thought was really great. but a few weeks into it i found out he was Domming other girls. Now i would not have minded had he told me, as this was just me spreading my wings, but the fact that he lied was a big no-no. And what everyone has said is true. if he lies once it is bound to happen again. i understand your need to find out the reasons why, but dont hold your breath for an honest answer, you may never get one.
When you find someone else, not only ask them questions but find out who they are frpm ppl they know. When i met my Master, we played online a few times and there was a girl who he chatted with as friends alot. so one time i pm'ed her and asked about him. she told me he was a reallt great person, a good friend and a person i could trust. i took her advice and never looked back. point being, ask a lot of questions a good Dom wont mind them, they will appreciate the fact that you are careful. If you find out they lie, its time to move on. just my opinion though. Good luck