masculinity and femininity

my husband and I have been having an ongoing discussion that I think y'all would have some interesting thoughts about: Does femininity and masculinity really exist? How do you define it? He agrees that he feels masculine but when we try to break down what exactly that means and why he feels masculine, we just can't explain what it means. The terms aren't about physical strength/nurturing/outward appearance/emotions/perception of the world/ability to bear children or provide sperm so the best we can come up with is that it's to do with a certain comfort in who you are. But that's got nothing to do with masculinity or femininity, just about being a fulfilled person regardless of gender identity. So we come back to square one with our discussion.

for some extra context, he's got a muscle disease that means I'm the physically strong one in the relationship. he's super empathetic and in tune with emotions, and also does most of the cooking and cleaning in our house. yet I feel feminine and he feels masculine.

What do these terms mean to you?