Hi ,
I am going around with a straight girl for almost 1 and a half years now. I met her 2 years back on an online blog and we started chatting. Because of the email id I was using she took me to be a guy and I maintained the misconception cause she was so damn attractive and we ended up chatting online almost every day . And finally after 3 odd months I felt too guilty cause we were sharing intimate details and I had become attached to this nameless faceless person. So , I finally blurted out that I was a girl quite sure that it woudld be the end of it. But given to the girl she is.. we continued chatting. Well not our usual talks cause she told me upfront that she is straight and we cannot have the same conversation. So , that went on for a month.. but we were back to our flirtatious conversations. We met after few months.. and well now we are involved.
My girlfriend tell me that she was so much attracted to the personality I am that gender doesn't matter.
She loves me . What I know is she won't cheat me . But I have my fears.Is it possible for a straight girl to be in a relationship with me? She has never been attracted to any other girl.. and since we have been together she has never ever been attracted to any girl. I fear that one day she will realise that this was a passing phase and it is actually men she can be satisfied with. That day will be devastating for me.. I am confused. Should I call it off and fend myself from an inevitable heartbreak.. cause in past I was with straight girls who broke my heart and treated me as some experimental toy

Its very hard to give you a specific answer because everything depends on the girl. :-( But, if I were you, I would enjoy what you have right now without putting any pressure on it for tomorrow. It may end in heartbreak, but you may end up being the girl of her dreams! :-) either way, you will never know, with her or anyone, if they are the one for you if you don't give them the chance to be that one!

After all this time, she may be OK with being bi, or at least think she can be. If she is completely straight, no it would not be possible.

Sexual orientation isn't a matter of black and white, it's a continuum of shades of grey. Just sounds like you're more to one end of the spectrum and she's slightly nearer the middle. Enjoy what you have; it's a precious thing. In straight/straight relationships we run the risk of our partner finding others attractive, but it's something you live with. Don't worry unduly about something that might not happen, but if it bothers you, she's the one to discuss it with. However, over-analyzing might put pressure on your relationship.