If you get logged out of your account, you will need to get back to the login screen. Here is what you need to do:
Tap More
Tap 'Me'
Scroll to the bottom and log out to return you to the login screen
Tap 'Already have an account?'
Enter the email address you used to create your original account and follow the prompts
If Cupla does not recognize the email address, it could be that you originally created your Cupla account using your Apple ID. Cupla is unable to confirm this as Apple obfuscates the address, so please try this, before contacting support.
If you still cannot access your account, please ask your partner to follow these steps:
Tap 'More'
Tap [Partners Name]
Tap 'Share login link with [Partners Name]' and send the link via your preferred messaging application
You will simply need to open the link from your mobile device with the Cupla App installed for the link to work.