Not easily from what I understand, either currently or after the upcoming Photos apps comes out on OSX.
Your iCloud Photo Library is tied to your single iCloud account (similar to how Photostream works), so you would have to use the same iCloud account - also sharing all of your email, document data, etc. I actually tried that for awhile a couple of years ago with photo stream, and it wasn't worth it.
The only official option is the Family Photo Stream, but it appears both of you would have to select each photo manually to send it to the family stream - and most importantly - it treats it really just like any other shared stream you could create right now. It doesn't go into your actual photos, it stays in the shared tab, and I haven't confirmed this, but I can virtually guarantee those will not be full resolution files.
I too am looking for a way to combine my wife's photos with my own - we often take multiple photos at the same time at parties and such, and I just want a way to merge them all so we can delete the bad ones together, while having all of them available.
From using iPhoto, and many Apple solutions (and attempts at working around the limitations of those solutions) in the past, I've gotten pretty good at reading what they are doing. At this point, my best hope is that once it's all done (iCloud Photo Library is out of Beta, Photos app is fully on OSX), we will not have what you and I really want, but a close second. The final process likely will have my photos synced via my iCloud Photo Library, my wife through hers (ugh to double iCloud payment of large storage), and then I will just have to periodically import her photos manually via USB to my Photos app on OSX, and she vice versa. At least at THAT point we will each have all of our photos synced in our own (separate) Libraries, and I can delete the ones I want and it will remove them from all of my devices, and she can remove the ones she wants from all of hers.
I've done extensive attempts at trying to semi-automate or fully automate this over the last year, to no avail - and it doesn't look like the addition of iCloud Photo Library, Photos App on OSX, nor Family Photo Stream will really change this issue from how it is currently, in terms of combining our separate camera rolls. I've tried dozens of options, apps, and attacking from different angles.
But at least once I do manually combine them, I will have them synced everywhere on my devices, which will be an improvement over the current situation.