Hi Cat, here is what I wrote in a different topic today. Perhaps you could talk to him/her and see if they would be interested in removing other friends (assuming those are not his/her 'actual' friends) so you two would be in the same league and enjoy the game more.
"My brother has two teams on the same level and server as one of my teams. All three have been in the same league and Champions League every season (6). The only thing you can control is that neither you nor any of your friends should have any other friends on that level and server because that could cause problems. If your friend has two other friends and those friends have other friends then Nordeus cannot fit everyone in the league of 14 teams. So tell your friends to remove any other friends and do not accept any friends requests. Again, I don't know if you guys have any but if you do, that could be the reason for it.. "
With that said, you guys could very well end up together. My guess is that your 'actual' friend has other top11 friends and because of that he ended up in a different league.