Love / My wife is Polish and it's difficult for her to open up and talk about her feelings [14]

Some background, my wife is born and raised in Poland. She speaks, (of course) fluent Polish, English and Russian, (I guess she's old school), we met got married and and now we live in the US. We have been married for awhile but have had an on-going problem with her being able to open up and express what she is feeling. I was just in Poland and she seems to be be able to talk it up in Poland with her friends and other Polish people. Her English is fluent enough so that I'm sure that she is not translating Polish to English in her head. I guess my question to the Polish woman is, culturally are Polish woman less open about their feelings and what is going on inside. Or is it Polish women tend to less expressive and more dismissive of themselves. I really just want her to speak what's on her mind. We've been married 5 years and it's still a big problem. Or perhaps even though she speaks good English perhaps she still at a loss of expressing herself because it's not her "First" language? Maybe it's not cultural Polish problem at all and just hers?