I just recently re-listened to The Two Towers so looked into 2). Tolkien discusses what happened to the Entwives in a letter, according to the LOTR wiki, and tbh I prefer to not consider that version canon lotr.fandom.com/wiki/Entwives

Entwives

"You see, we lost the Entwives." —Treebeard in The Two Towers Entwives were female Ents. They were put upon the earth by Yavanna to protect her trees along with their husbands the Ents. According to T...