I read this short story (or perhaps novelette) at least 20 years ago, probably more. I suppose it was in a collection, since I very rarely read magazines. I don't remember if I read it in French or in English.
I don't remember much. A "normal" man meets an alien who looks almost identical to a woman, and is very attractive. I don't remember if it is a SF horror story where he got to a different planet by spaceship, and was astonished that locals were so similar to humans. Or it is a Fantasy horror, where he traveled by ordinary ship to some unknown island (or maybe by land to some very isolated place, but this seems unlikely) and only later realised the inhabitants were not "normal" humans.
IIRC, he takes her with him on his return trip. He has been repeatedly warned, either by his human travel companions, or by other alien "locals" not to have intercourse with her. But he did. I don't think he raped her. I even think she did a lot to persuade him against his reluctance to act against the warning he had received. But I am not positive about that.
Anyway after a short pregnancy she delivered dozens of homunculi who rapidly took over the spaceship (or regular ship - or possibly whatever land transport was used, but that does not look likely).
When he saw what had happened, I think he committed suicide.
EDIT
Emsley Wyatt suggested "The Lovers" by P. J. Farmer.
The character Hal Yarrow reasonably fits my memory. What does fit is the mysterious way he met Jeanette, and his subsequent relationship to her is just as I remember.
So he did not commit suicide after she died giving birth, but the suicide may be a false memory.
Thanks to user14111 I have found the short (novella) version of this story. I am sure I did not read the novel version, and anyway it could only be worse.
It is not my story.
Something does not fit at all. Jeannette's offspring have to be put into an incubator. And the story continues many pages after her death when delivering the "larvae".
Maybe the man does not commit suicide. But my story ends rapidly after the birth on the dozens offsprings.
And I remember clearly that they are immediately active.
They might be "technically" larvae, like locusts larvae, not "imagos" because without sexual organs, smaller than adults but otherwise looking like them and immediately active.
Can anyone propose a totally different book ?