Maybe it's just my weird perspective, but aren't all relationships this to one degree or another? Culture is a product of a shared society, but our interpretation and adoption of that culture is an entirely individual process, and we are all unique and define ourselves in the ways that best suit us.
Honestly I've never really thought about it because I generally don't place much importance in these things - I see people as individuals and the products of their own choices rather than the circumstances that life placed them in. If things like their religion, racial identity, or historic culture are important to them I can understand and respect that, but I've never really seen those things as defining aspects of their personality, and certainly not of our relationship. All of the relationships I've been in have been with people who have been very different to me in most aspects, but I didn't - and don't - place much importance in it, because the foundation of those relationships is what is important, and that's based off of mutual appreciation, respect, and understanding.
Maybe I'm just weird though.