Since you are able log into your account on your boyfriend's console and play without issue, it doesn't sound like an account issue. It may be a network issue. We can assist with providing tips on how to optimize your network set up.
First, you can always check online services status here Call of Duty: Black Ops 2 Status
If online services are fully operational and you are still unable to connect, you may want to try the following.
- Reboot your router.
- Try using a wired connection in order to sustain the connection quality.
- To help identify if there is an issue with the router or blocked ports, try connecting directly through the modem.
- Check the NAT type. Is it Open, Moderate or Strict?
- Establish a static IP address and port forward.
Here are the port numbers you will need:
Xbox: Activision Support
Should you have any questions on how to port forward, please contact your ISP or the router manufacturer.