This question might be too abstract. But it seems like people look for different aspects in romantic relationships. There are the ones that are drawn to opposite traits, ones seeking excitement, ones that wish for a stable anchor in their life, etc. And most of this happens subconsciously – or it does not. Maybe you have a different approach to love. Tell me about it.
Its a cultural paradigm we overlay on top of the hormonal responses we’ve developed over milennia, in order to reproduce and then give our offspring the best chance at doing the same.
As evidence I’ll suggest that even today’s cultures have different concepts of “love”, but this is especially true as you look back through history.