Why do you think her mother said no? Did you do something to upset the mother? Do you have a stable income and your own apartment? There has to be a reason the mother said no. I talk with my mother frequently and ask her for these kind of things too. Not because I am a child, but because my mother knows what it is like being married to a loser/asshole. Why don't you sit down with the mother and have a talk about this rather then coming on her complaining about how your girlfriend trusts her mother advice.

As much as this might suck for you at the moment, you should really be grateful. If she is really that dependent on her mother, enough that she would have to ask permission to get engaged, then you really don't need that in your life. I'm assuming that you are both adults, so the fact that she asks her mom permission for something like that, and probably everything else, is alarming. I'm sure that you love her, but this sort of unhealthy mother/daughter relationship is bad for any other person who may be involved. Take it as a sign that she's not the one for you. Sorry, OP.

that's a clever way of not having to say no directly.

sounds like my ex...

Should ask her what she would do if her mom died? Who would she depend on then?

Maybe you should cut it off anyways. Or take a long vacation away from the mom.

Don't marry a person who is not independent!

I ended a relationship recently for this exact reason. Run dude, you're dating Norman Bates' twin sister.

youre supposed to ask her parents for their permission to marry her anyway

All I can think of is, "why you gotta be so rude?"