Taking a guess that in her family, talking about problems may have ended up making things worse.
She either fears your reactions (because of the reactions of others in the past), or feels shame about her thoughts or feelings (not necessarily rational shame, could be something quite minor.)
Best way to overcome fear is to face it.
You sound to me as though you can already handle discussions very well, so just be with her while she struggles with herself, and keep gently encouraging her and being willing to sort it out. Eventually she will realise that it really is OK, and even preferable, to talk about it.
She might be taking after her mom, too; if you quit, she wins.
I did counsel as a trained volunteer (Rogerian method) for Lifeline in Australia for 2 years or so... have also done lots of work on myself. You're welcome to contact me any time if you feel like it. Thanks for your very nice words. :)
I don't like talking about things I can't fix it is a total waste.I myself hate stress I try to dodge it and it is wonderful,I know where she is coming from.
My wife is the same sometimes, what I do - Drop the subject and attempt to make up, keep cool, wait for a "good day" and broach the subject again if she seems happy to talk about it I press the issue and be ready to back off if she seems to be getting tense and return to the beginning again.. eventually I can grind away at her until all the "getting around to how we are going to talk about it" has been worn away and we can actually discuss it. Usually the issues have been financial (on both sides) or the kids. Basically keep grinding away at the problem, being gentle and understanding as you go.. you can't be male about it, just makes it worse.
Oh, big advice, if you've been in the relationship a while you should know what her "triggers" are, words or phrases that will set her off, you can be sure she knows yours.. avoid those at all costs.
Relationships are work, love is an important aspect of it but second to the work involved in keeping it together. If the rewards didn't justify the effort no one would be in one for longer than it takes to procreate.. thank goodness a stable long term relationship (hopefully life long) is well worth the effort that goes into it. All pain fades and if (as I sincerely hope you do) you can both keep it together you'll both look back on these days as a minor hiccup on the road to happiness.. trite I know but sometimes trite works :)
ir, from all that you'e said here it sounds to me that you've ceded all of the power in this relationship to her, and I don't imagine that "solving" that problem really interests her. You can't "make" anyone happy except yourself; she determines what makes her happy. Myself, I'd bail, but if you enjoy riding the emotional roller coaster, go for it.
I wish all of the best for you, ir.
give her a hug and tell her you're there no matter what :) and if she can't talk about it let her write it all out and you can read it later
If you want to make the relationship work, let her either approach you with her problems on her timetable (as long as you are not harmed) and be the calm, steady, manly stabilizer, or (gasp) leader. If you don't think you can continue the relationship with her as she is now, tell her such.
Get out while you can. A year? F*** that. Tell her to grow up and tell you what the problem is or else you are going to assume that it's fine. Remind her that you aren't a mind reader.
Although... If you've been together for awhile - everyone's getting engaged around you - you haven't really talked about anything like that - and 'if you don't know, I won't tell you' is the attitude... Well. She might be wanting some massive show of committment or something. I don't know. I'm not a mind reader either - but this has been the cause of a couple of my girlfriends melt-downs recently.
Good luck man.