I think she meant more like, even though Suwako cums in Sanae's mouth, there is still the chance that Sanae is impregnated. It is a low chance, but precum can have some 'tadpoles' in it, and those can reach the egg, and fertilize it.
Remember kids, coitus interruptus is not a fail-proof method.
Sanae-!
twiceComing-!
Open your mouth!Suwako-sama's semen is thin, but there's so much of it...
She always tells me to swallow, but......I feel like even if I swallow it, I'll get pregnant.Swallow it, okay?Ah! ♥
Mm ♥
Eh, okay!Uwah...Even so... I just can't...
Get this taste off my mind...Here it... comes... Sanae...!
