I am Indian. See what i feel is that don’t hurry for marriage until you are sure about that person. It is something doubtful is he has not yet introduced you to any of his friends, family members or colleague. Who knows if he has another girlfriend or wife? I don’t want to shed your hope but it is better to be sure. If he has decided to spend his whole life with you then there is nothing wrong to let you meet all close people related to him, whether they like you or not. i feel you are not at all wrong in asking him to associated your identity with him in public. If your mother is her FB friend, you can send FB request to her sister as well. and FB is again not that big Trustworthy source. Please meet people close to him before marrying him and ask them to witness your marriage. being cautious for yourself is not wrong. infact it is your duty to take care of things happening to your life. it is about your future and no one else would be more concerned than you your self.
And yes don’t become so negative and hopeless with my view. Take things sensitively. i am just concern about you but that doesnt make the person you are going to marry as fake. may be his reasons are strong for him. but if his sister is close to him and also his friends… they all should support him and he should let you meet them.
don’t be rude is asking this but also remember it is your right to know.
Good luck. Hope to see you replying with a happy note. And all the best for a happy married life.
see my blogs to sooth urself