donrae
Rest in Peace -2017

That first bird you posted is a cockerel. He's not really a red sex link, that's a one time cross of a gold rooster over a silver hen. Looks to me like someone didn't know it was a one-time deal, and bred a sex link to a sex link, thinking they'd then get sex links. It's not the case, you lose the linkage of color to gender in the second generation. You can see the darker, glossy feathers on the wing bow and in front of the tail, those are male signs. You can also see how he looks leggy and kind of gawky and unfinished, where you hen is smooth, rounded and feminine looking. That was mating behavior you saw.
where are you located?