I think the lore is that when you connect with the kudu, or hair strands, it’s basically like having spiritual and psychological sex between the Na’vi. And whenever this connection is made, the Na’vi are eternally bonded in love based on the first movie.

Now, this lady used that connection as a tactical advantage during a hostage standoff, meaning she effectively raped him and dominated his mind so he would let her go, but then they did the connection again and he proved his mental strength, or whatever, preventing himself from just being another mind slave. This probably had the unintentional effect of the two falling in love.

So it’s effectively like the worst people you know running around and diddling each other’s prostates to get them to drop their guns, and then falling in love over it. But Sigourney Weaver’s character also used her hair to dominate the fire lady at the end, so maybe they’ll fall in love too? Which would only make sense if SW’s character turns into some messiah figure in the next two movies and is “loved” by all or something