Without getting too political, I assume that men are way more likely than women to be concerned with traditionalism and nationalism, and they tend to intertwine it into dating too. I have included two twitter examples here which show that it's quite universal, example 1 and example 2 (and also a similar, but different, example 3).

These types of attitudes from men are also reflected in the posts I've seen made by men on /r/WhereAreAllTheGoodMen:

For example, on the post of a 19 year old girl who was impregnated (her dating profile here), a user commented a long post citing statistics and documentaries. Like....... why is he so invested? Men who are out there having a successful sex life would not be giving so many fucks like this, imo.

Just like how men being insecure over a woman's n-count publicly or with her would probably be considered unattractive by most women, I think there is a trend moving towards women finding this behaviour unattractive too. The reason why I state that it is a trend is because I assume women would've previously shared the same view, or at least pretended to. Would the dating market change in respect of this?

(I mean, based off couples I see in the UK, it does seem to be increasingly the norm to find interracial couples. And women with mixed kids could still find a man whose race doesn't reflect those kids, I've seen it plenty of times. So it just appears to me that it's the leftover men trying to clutch at anything to make themselves feel better, when they could just spend that time by not caring about her exes and actually having sex/relationships).