If you own an Android device (and iOS or WP8 but it's most noticeable with Android because of the widespread use of gmail and its tight integration into Android) then the account you use to sign in on that device becomes incredibly precious. If you also use that address as your regular email you are opening yourself up to spam, clicking phishing links and the like. Once the spammers have your email address then it's worse than useless - all the addresses in your address book are compromised and the owners of those addresses won't want to open emails from you - that's if they even see them if they have them go directly to trash. Now you're left with a device no one wants to know and which has all your app and music purchases tied to it. You don't really want to factory reset and start again do you? The hell no! So don't use the Android sign-in address for anything other than device related matters such as the app store, Google Music etc. Google hasn't particularly written its music store software to protect your gmail account. If you and your spouse share the music account s/he gets to know your password and can access your emails.
Now, last time I mentioned this there were howls of outrage from people in happy marriages saying things like "if you can't trust your husband/wife with your password then your marriage is in a sorry state". That isn't the issue with sharing passwords - the issue is if you do share then there is twice as many opportunities for your account to go bad; so don't do it. Instead create satellite accounts. If your device email is email@example.com then create another account called firstname.lastname@example.org. One for apps called email@example.com. as many as you want. Give your spouse the password and let him add it as an associated account to his phone - you too. Google lets you have sub accounts on your phone and on balance it's a good idea because it gives you a lot of flexibility in how you manage your devices.
Your device email address is synonymous with your device. If someone controls that email then to an extent they're controling your device. If you think someone may easily guess your email address - you have to be on gmail so that's half the guessing solved - and your name is donquixote or something relatively unique then you may just want to use a random and long string for your ID, similar to a password but with the username character restrictions. You're not going to be giving it out anyway - it's basically just the name of your device and no one's gonna guess firstname.lastname@example.org. Then, never use this email address for communications and never give it anyone. That way your precious email address never ends up on anyone's list or in an address book.