I am of the opinion that having more than one bird raises the potential for more harm than good. Between disease, injuries, "random" aggression, sexuality, over-bonding etc, it is indeed complicated.
That is not to say that it cannot work, but never get a bird for your bird (nor assume that your bird will take to any new bird in its home). This assumption is dangerous for all involved. Never get a bird for your bird unless you personally are willing to devote the time needed to caring for 2 separate birds in totally separate spheres (as this is the necessity in the worst-case-scenario--e.g., separate out of cage time, separate play, separate everything)...Even if 2 birds seem great at first, you can NEVER let your guard down---which is problematic when you are dealing with an already high-maintenance pet. Toes have been lost, birds have died, and owners have felt abandoned by their old companions with the introduction of new birds. In this case, you are worried you don't have time for one, so getting a second could mean double the time you already are taxed (if they don't get along or if they get along TOO WELL).
Again, not saying it can't be done...It is just a massive gamble. Many do make it work, but you have to be in it for the birds to see it through and willing to deal with the potential for added stress etc. If you work, I am not sure where you would find the time to deal with 2 birds independently (if they didn't mesh).
If you feel like your bird is lonely, you have to understand that any acceptable filler will replace your bond in 80% of cases...So, if you are gone enough that your bird IS lonely, you will be less important to your bird than a bird to which it bonds. That is not to say that a new bird will bond with your bird (again, they often hate other birds or behave in unpredictable ways around them) but if it does, you may not like the result. They can also start laying eggs and become aggressive due to the presence of another bird.
