I'm not good at screenshots and the like, but I'll walk you through how I think it will work for you and then tell you how my wife and I have ours set up.
First I'm assuming that you both have a Gmail account. If not, I think you can share one for the calendar, but email would get real confusing (I think). Start by going to the calendar you want to share. Click on Settings (upper right corner), then click on Calendars. Click on "Share this Calendar", enter your financee's email address, choose which permissions you want to give, and click "Add Person". That should do it. The person who's email you entered will get an email telling them they have permissions, and if they use their own google calendar, google will automatically add it to their calendar.
Now if you don't already have Google Sync on your Curve, you will need to download it here. Once it is installed, go ahead and run it on your BB. I don't have the exact steps for setting up the calendar, but it is pretty straightforward and simple.
Here's from the Google sync page:
[QUOTE]After installation, you can find the Google Sync icon on your home screen. To start using Sync:
Click the icon (you'll see a screen with a login form).
Move the cursor to the login section, and type the full email address of your Google Account and your password.
Press Login and Google Sync will sign in to your account. Once you're successfully signed in, please read the information on the Welcome screen carefully. If you wish, you can make changes to the default settings by clicking on the scroll wheel and selecting Options from the menu. Both Calendar and Contacts syncing are enabled by default for new users. (If you're upgrading from the previous Calendar-only version of Google Sync, you'll need to enable Contacts sync.)
Click the Sync Now button at the bottom of the Welcome screen.
The initial synchronization will take some time, depending on the number of events you have in your Google Calendar and the number of contacts in your Gmail Contacts. Please be patient; you can allow the synchronization to take place in the background as you perform other tasks on your BlackBerry device.
To use Google Sync, click the Google Sync icon on the home screen of your BlackBerry. Alternatively you can open the calendar application on your BlackBerry and click the thumb wheel once to pop up the menu. You'll find the "Google Sync" entry at the top of the menu./[QUOTE]
Once you have it set up on both BB's you should both be able to make changes, and have the other see those changes. My wife and I have separate Google Calendars, so we just have our default calendars set so that each can view but not make changes. I can see her basic schedule (dr. appointments, dinner w/friends) and know what we are doing throughout the week, but if she puts something on there like "Bring book for friend", I can delete it on my BB, but it won't delete on my Google calendar since I cant make changes. This works great for us, since we really use our BB's more than the online Google calendar.
An example, this morning I scrolled through my calendar and saw that she has a dr. appt. tonight after work. Now we also have other alternate calendars set up on our accounts; these sync only to our respective phones. I don't need to know her student tutoring schedule throughtout the day, she doesn't need to know what special activities I'm planning for my students (at least, she doesn't need to know on her BB!) Hopefully this makes sense. Really, once you have the calendar set up on Google, and Google sync set up on the BB, play around with it. The options are pretty easy to follow.
Let me know if you need more explanations, I'm glad to help. I've learned so much here just in a month's time, I'm more than willing to give back.