Chivalrous - What does it mean?

I can infer only two things here

1) The man is chivalrous - Being courteous, especially towards women (weaker sex???). My point here is, the girl in the picture is not incapable of sitting on chair.. So why gender stereotyping?? It does not make sense. However the following picture does makes sense

But no body reads the above picture as being chivalrous... It is plain humanity to help people in need....

2) Expression of love

I googled a lot to find the picture of a beautiful young girl making a handsome fit boy sit on a chair.. Could not get...(In fact I found the same set of pictures of a man helping a woman to sit on a chair. Try it yourself). If it is expression of love and gender independent, I should have got the picture as easily as I got the first one... However, I got a lot of pictures like the one below. In fact roughly 50:50 ratio

Having said the above, I find the below picture interesting

But I would not call it "Being chivalrous"... Why?

Let us assume for the couple in picture and at that point in time, it is easier for the man to carry heavier load than the woman. So it makes perfect sense for him to carry the load. But I need to be careful about this picture. Am I stereotyping the difference in physical between a man and a woman?

No..... I don't think so

Though it is statistically true, I am not stereotyping. That is why I mentioned 'for the couple in picture' and "at that point in time". It would equally make sense for the woman to carry a heavier load if she was stronger.. In future, the woman (in picture) might get stronger and carry the heavier one.. Who knows what is in store for future?

Have a look at this picture

Again we would not call her chivalrous for sparing the man the trouble of child birth. It is just that 'at this point in time', it is not possible (mostly) for a man to give birth.. So it makes sense for a woman to give birth.. Who knows what is in store for future?....

So.... What is being chivalrous???