confused - 2x independent groups or matched pairs experimental design?

for our coursework we did a covert observation of mobile phone usage in feminine and masculine presenting people. i missed when we covered our methodology, so when i asked my teacher what inferential test we used she told me mann whitney u - ordinal and independent groups. i'm just confused as i would've thought feminine presenting and masculine presenting would be matched pairs? or is it two independent groups? we recorded with event sampling, tallying behaviour observed, i would've thought we'd compare using matched pairs inferential test with an average of feminine and masculine? just a bit confusing, could do with some help! I could also see independent groups, i think it's the difference in gender presentation throwing me off as usually that's a matched pairs thing.