Don't want to marry my girlfriend but don't want to tell and hurt her

Iam a goan and my girlfriend is from punjab, In the beginning of our relationship everything seemed fine but now I feel I don't want to marry her as she is working in bangalore and m in goa, marrying will spoil either of our careers plus there is a huge culture difference between our families. Our families have agreed for our marriage as we pressurized them to do so. But now m very skeptical about the marriage and really want to call off the marriage. But doing so will hurt both, her and our families. . Please suggest some way to call off the marriage and not to break her heart

I'm also in a relation with my bf who is north indian and im from south. The reason you specified here seems unconvincing to me.
You love her, and made families accept after so much hard work. Now they are ready inspite of the differences, but you are not?
But you knew everything about her then only you took this step? right. Did it not strike to you that both cultures are different that time?
What if you both are working in different places? You can always move to somewhere common for both of you. Or you could plan to stay separate if it is okay for both of you. Else either of you can sacrifice your current job and look for new one in another place where u both agree to stay.

By marrying her you can learn her culture,festive and she can learn yours. This will help you both experience new things in life. Cultures and caste, religion all are man made and materialistic. Please stop thinking it as a driving force for life with someone whom you love. Job and workplace should never be a issue to turn down your love.

Your question how to cancel marriage without hurting her? That is never going to be possible, you are going to hurt her big time and it is not under your control. You can sit and talk with her and sort out the problems or doubts or any fear you have. You can postpone the marriage until you sort things out but with mutual consents.

In my case my parents and his parents can't even talk because they dont know our lang and mine dont know his! Even english is also not possible. How do u think such case is?

But breaking up with her and losing her over a petty thing does not sound reasonable even to an outsider like me. I think you should sit and think about it is is worth losing a person in your life? Whatever decision you take make sure you donot regret for it in future. Even after all you think it is not going to work out and you are so certain about it then please tell her as it is, there is no shortcuts or no pain ways here.

I feel your reason is unclear here. I'm southie and my bf is from north our families cant even interact due to language barriers. Talk about cultural differences! you get to learn and experience new cultures here. Also you knew well about all this before loving her and now what is troubling you?
You can sit together and work out a common situation for both of you. Either of u can sacrifice your current job and move into one city where u both can work. Else you can stay separate and continue with your work with mutual consent.
Why would you want to throw away all that hard work and love of your life over a silly reason?

You should sit and talk to her discuss what is bothering you, you will come across something!
But if you are already made up with your mind then just go tell her as it is. There is no shortcut or painless ways to let her know. You are going to hurt her big time so be mentally prepared for it.

My suggestion - Never take a decision that you will regret in future!