If you want a better adaptation, watch the 2000 miniseries version of it. It ran to nearly 5 hours and, contrary to this movie, your girlfriend won't have to wait two years to see how it turns out if she isn't interested in reading the book herself.
How can you watch the 2000 mini series version?
I looked at all the streaming services and media vendors, and haven't found a way to get it.
It does seem like Dune would be better served by a mini series....perhaps 10 or 13 hours of screen time for the first book.
Didn't you get the memo? The streaming industry fucked up, it's back to torrents again.
Edit: On DDG, search "dune miniseries <file-extension>", the second result has a working magnet link.
No idea, haven't searched for it. I bought the DVDs years ago. I just figured someone would have it out there on the Internet.
1. The plot was moving too quickly and without enough context. She said she didn't understand much, and I can relate to that. If I haven't read the book I wouldn't be able to pick up with the plotline.
2. We didn't have any feelings towards any of the characters. We weren't sorry for Leto, we didn't identify with Paul, Jessica or any other character, we weren't even hating the Harkonnen.
All this led us to the conclusion that it was better to take things more slowly, investing more building the characters and context and getting people "onboard". This would have probably required to split the book into 3 films instead of 2, but I think it would have been worth it.