I'm not so sure that lying is a big part of it. Perhaps not being entirely honest about things, like you said. I think it's more behaviour in general, we can be very demanding of people without realising it.

From my therapy, the main thing is it's difficult for us, is to gage how intense we are being when dealing with other people. Sometimes we might go in all guns blazing and other times not say what we are really thinking. Getting caught up in the moment with our emotions rather than being rational, or the oposite being very senseless and cold.

I wonder with the attention seeking thing, how she would be getting attention by being dishonest and leading you along? I think the main danger would perhaps be getting too attached and then the relationship souring later and becoming a problem.

In terms of a romantic relationship with two BPD sufferers, it could be potentially damaging to both of you, so be careful. I probably wouldn't use my real family names on the internet so I can understand why the names might not match up. Perhaps you could ask her about it and say that you noticed she had been posting on another site? I think the best thing would to be honest with her and talk about all your fears.

Jim