>>281689998 (OP)
She probably is simply wrong on that.
You see she had an entire village of elves, but the demon kings orders were to exterminate all elves.
She also rarely met other elves, there are literally centuries between her meeting Kraft and another elf.
Villages are easy targets.
Another thing is she obviously was a young child back then.
There are some indications for it.
For example her mana was comparable to a seasoned human mage, which would indicate she has about 60-80 years of life behind her.
Yet this does not completely correlate if we factor in Fern as a comparison.
Frieren said she was the strongest in her village.
So assuming Frieren was somewhat talented and spend time training her magic, she might not even have been 40 years old when Flamme found her.
From Kraft and Serie who both perceive Frieren as young we can see that what assumingly is an adult elf their physiology is closer to an adult human.
Frieren shows actually signs of a girl entering puberty, like her actually having developed a sorts of breast envy in regards to Fern.
Frieren has actually if you think about very little knowledge about how elves are and were.
She lost her village fairly young and in life rarely met other elves, so her entire perception about the reproduction thing might be false.
Even on travels you would rarely met pregnant women, because of the dangers, so traveling as a pregnant elf as species the demon king designated for extermination is double dangerous, but so is being in a community and staying in one place.
So pregnancy for the species in itself became very dangerous.
On a side note I find Flamme very questionable.
She just so luckily happened to appear before Frieren after the demons wiped out everyone else in her village.
The fact she questions Frieren about how she perceives the demons as if to make sure enough unquestionable one sided hatred is installed into her.
As well as her apologizing to Frieren, was it it really for the burden of solitude.