icloud- use with different apple id
Yes, you can create a shared photostream and invite her.
To create a shared iCloud photostream, you have to check that you have enabled iCloud Photo Sharing (Settings -&gt; iCloud -&gt; Photos -&gt; Photo Sharing). Then you can create a shared photostream by going to the Photos app and tapping the + button in the Shared tab.  

The only disadvantage of this solution is that you have to add new photos to the shared stream by yourself. (The automatic photostream works only across tow devices when you are using the same Apple ID)

If you want her to get your photos automatically, you can use Dropbox, as heir app has a auto-upload feature and share the dropbox-folder with her. The question is if you want to save your photos in a dropbox account.  

I hope my answer solves your problem.