Boy/ girl relationships at age 9? What's your experience?

[Legacy]

There is a girl in DS's class (Year 4) who is really keen on him.

He likes her too, and says he wants to send her a valentine.

His conversations recently seem to have been peppered with references to 'people having girlfriends' and 'love' etc.
One of his friends has a teenage brother, so I think it may be coming from there.

No discussion of sex (which he still thinks is 'disgusting - I'll never do that' ).

Just wondering if this is normal, developmental stage for this age group? My recollection is that boys were only interested in science or football at this age?

My nearly 9yo dd appears to have a stream of boyfriends, and most of it seems to be driven by the boys (who ask her to be their "girlfriend" or similar. one kissed her behind the bushes, which shocked her rather). She sees them as friends but the boys seem to see it a bit differently.

It's surprised me. She's very ungirly, always messy, the sort of child who won't wipe her own nose, and likes playing with things like marbles, mud, animals, scaletrix, so she gets on well with the boys, but I wasn't expecting this influx of "boyfriends".

Sounds normal from the girl side, but my 9 year old DS would admit to liking girls

But he's a very boyish boy - into footie, dirt etc. Is your DS more intellectual, sensitive - they seem to be the sort the girls like at this age?

oops - my 9 year old DS wouldn't admit to liking girls !

Ds in p5, has just turned 9 (one of the youngest in his year) has no interest in girls. He's good friends with a few girls, but no talk of girlfriends yet.

ds2's best friend is a girl (both yr5). I think his friends egg him on that she's his girlfriend, and I think he enjoys the 'cred' that gives him, but I don't think he really thinks of her that way.

I'd be astonished if he'd thought of valentine's cards, and I'm certainly not going to mention it to him.