Intercultural or cross-cultural relationships bring both challenges and opportunities. While it may take more time and effort to understand one another's perspectives, needs, beliefs, and behaviors, drawing on multiple cultural references and perspectives can be enriching, leading to growth and more intentional living.
Just like a fish would have trouble describing what water is like, because it's the context the fish lives in constantly, it can be hard to explain the customs, expectations, and values that come from our cultures. Having a cultural lens can help build understanding. Fons Trompenaars, in his book, Riding The Waves Of Culture provides a helpful taxonomy of seven dimensions of culture which can be useful in identifying and understanding differences, and also rates different countries' cultures along these dimensions. For example, he distinguishes country cultures between being emotional and neutral, which might contribute to understanding partners' different orientation to emotions. It's important, though not to stereotype or assume that because we know where someone is from, that we know where they stand, automatically, as various other influences may be at play.
Dr Luma Sumjee, a New York Clinical Psychologist who specializes in working with intercultural relationships and commentator on NPR, in discussing meeting your partner's parents, validates the idea that knowing about their culture is only the first step. She recommends using storytelling as a way to expose expectations which a partner and his/her family may hold which may seem so obvious that they don't think to point out. She also recommends (and I concur -- always safest, and most caring) asking first, rather than assuming.
A couple I've worked with, a South Asian cisgendered man and his trans female Latinx girlfriend discussed with me their differences regarding public displays of affection. He explained that in his culture, it's rare even to see family members kiss or touch, and that cultural modesty would inhibit any affection in public. After de-personalizing the difference by viewing it through a cultural lens, so that neither felt either blamed, rejected, or judged, they were able to decide as individuals and as a couple how they would most like to handle showing affection publicly in various settings including among friends, and with their respective families.