New Puppy Corgi - Friend for Current Corgi

Question
Hello,

We have a 3 year old Pembroke Welsh Corgi named Fox.  Fox is the greatest thing that has ever happened to us.  He has brought us unfounded joy and happiness that we never thought possible by owning a dog.  We bought him as a 3.5 month old puppy and we have had him now for the past 3 years.  Within the last year my fiancee has finished graduate school and is now working full time.  He has spent the last year dealing with us being away from home for 9 hours a day.  But there was never a problem with that, he never responded negatively to that.  He was always a happy pup no matter what.  Although due to the fact that he spends 9 hours a day alone, we thought it would be a good idea to get another Corgi puppy so that Fox would have a companion so that he wouldn't be alone during the day.  Well since the addition of the new puppy, Fox has seemed to become very depressed.  He doesn't act the way he used to.  He doesn't act jealous, he just isolates himself away from both of us, doesn't come anymore when he's called, he's not playful anymore, not spunky and energetic, just acts as if he's extremely depressed.  He doesn't get any less attention from either of us as he used to and yet nothing seems to help.  I don't know what to do, should I return the new puppy to the breeder? Will Fox eventually get used to her?  The whole reason that we got the addition was to enrich his life, and I feel like I did the exact opposite.  Please help!

Answer
This is a tough question.  It is hard to get inside those furry little heads.  At 3 years old, he is mature and settled into his routine.  Even dogs that welcome visitors, may resent a permanent, new resident.  I hate to say take the new puppy back, but maybe you had better while your heart can still take it.