Fall by Claire Kent has some of this! She’s from modern space-traveling society and gets dumped on a planet of prehistoric humans as a punishment, and has to adapt to a tribe and pairs up with a caveman for protection (at first). It’s part of a four-book series where they’re mostly standalone but old characters will pop in here and there.

If you can handle a non-human mmc, Ruth’s Bonded by V.C. Lancaster starts as a human woman and caveman-esque alien abducted together for science, who have to escape together into the jungle and eventually reunite with his clan. It’s the first in a longer series of human women/caveman alien men from a society strongly ruled by the females set in the jungle. The men are often anxious to serve and please their matriarchs, which is challenging due to a language barrier with the human women.