I am sorry for you loss. First off this is breeding season and most birds are act a bit "funny" during this time of the year. They are also going to morn just like people do, it sounds like your teils were best friends. I would suggest getting another cage to keep them apart for now, a tiel is alot bigger then a keet and you just can never be too careful. You can get some really good pricing on cages on EBay.