Sincerity can not to prove by talking. It to look at the behavior of them. Such as contact alway. It time we don't understand listen to reason of the other party and after talking for a while, we need to see each other. After seeing you and he contact you regularly as the original. And talk about the future. (such as to make you fly, etc.), etc. this can we called him sincere in the level
I never agreed to see anyone without a girlfriend or not yet real. Everyone who chat with friend. If someone wants to be more than friends, we must immediately flew to be studied. The to chat? Send short message length.But the need to talk through a webcam with always. We like to see the reaction of the other side while talking.