set up the calendar inside your google account and then so long as you both log in you can access it at all times I sync mine to my phone and we actually have a calendar per person that are diffeerent colours - wonderful system
calendar.google.com Then click the cog icon on far right to get a drop down menu, click settings. The click the word Calendars in the top menu, and click Create New Calendar It then gives you options, give it a name, select the people you want to share it with. Finally click Create Calendar. You now have a calendar which is shared with the people you selected/invited.