Is it easy to keep and save the relationships if you have different mentality?

Hi everyone ! This time I want to share something very interesting but that will not be my own experience that will be the experience of one of my friends who found the man in this dating place. This girl deleted her profile because she has found her love here and she shared her thoughts about new life experience and how she builds the new relationships with a man from a foreign country.
After three weeks of communication the man came to my friend to meet her in person in Ukraine. Everything went great, the lovable couple was happy during some days and then he invited her to come to him in his country. Being together for almost two weeks showed that people have really different mentality. Maybe this happens with all international couples when people have different traditions and habits in daily life. The problems started when the girl wanted to eat the food that she got used too… but in the local supermarkets she didn’t find the food that is similar to Ukrainian. Other bread, other meat, other kinds of cheese…. So she started to feel herself uncomfortable in such conditions where people got used to eat fried potato with big pieces of unprocessed meat unlike Ukrainian cuisine where meat is always well-prepared and the stomachs got used for the first courses like soup or borshch or even tasty okroshka.
Then the girl understdood that they have different views for the rest during holidays. People in Europe got used to travel by car but the majority people in Ukraine travel by bus and by train. So, for a European man it is not easily to understand this too how you can spend more time in the bus or train and waste a lot of time in the transport vehicle. But that is only because Ukrainian people have another way of life here and there is nothing bad that people travel by bus or by train. And these are only two examples where a lovable couple can find the underwater stones of misunderstanding. So how to develop further relationships and how to be happy when there is difference in mentality…. Actually my friend is a brave girl she decided to try her happiness and try to build further strong relationships with her foreign man. What will be then from all of this I will know later but now I am just thinking about – it is not easy to find a life partner from another country , it is not easy to meet each other … but at the moment when you think that everything is perfect and you can be together without any problems you face with OTHER SERIOUS PROBLEMS - different mentality…..Who can help to keep and save the relationships in this situation ??? maybe you have your own advice and you can help me and I will tell your advice to my friend?
What do you think ? Don’t wait for too long with this, ok ? My friend really needs a good piece of advice from an experience man….from youuuuu……
See you…..