Ask your wife to add her Spotify account to Sonos. 

 COuld you be so kind and clarify to me how that is done by steps. Not familiar with it. It would be highly appriciated

The exact same way you added your Spotify account.

As described in the multiple accounts per service FAQ. 

But get your wife to add on her phone.  If you use your phone you may find the service is not listed, or it tells you that you already have the service.

Hi @egillein.

Welcome to the Sonos community and thanks for reaching out to us.

I could not agree more with all of them. Allow me to share with you the guide from our support website on using multiple accounts for the same music service. The guide would show you the specific instruction on how to add another account of the same music service using the Sonos App. The guide would also show how to switch accounts on the Sonos app. Moreover, Adding another account of the same music service on the Sonos App is the same as adding a  music service. Let me share with you the step by step on how to do so.

1. Open the Sonos app.
2. Go to settings ( on the Sonos app, bottom right).
3. Tap on services (3rd option from the top)
4. Select add a service ( below music and content).
5. Select the music service of the account and follow the prompts.

I hope this helps.

Please let us know if you still have further questions or concerns. We are always here to help.

Thanks,