There are three books in this trilogy by Ludmilla Zeman - Gilgamesh the King, The Revenge of Ishtar and then The Last Quest of Gilgamesh .
We totally loved this trilogy. My kids spent hours looking at the pictures and asking me to re-read it to them.
Granted, it's a violent story so some of you may not want to read it to begin with. But it's handled really nicely and isn't all gory and gross while still retaining the original themes.
I do believe the first book is the one where "they explore the ways of love together". My kids didn't even catch that so I didn't dwell on it. It may become an issue worth discussing when they're older. The art is done in the style of what has been found during that time which was another way to learn about the time period.
I like to find children's books of classic/adult books and have them read it when they're young. Hopefully when they're older they will better understand the classic works because they are already familiar with the characters and plots. This series was exceptionally well done.