When I first got Marcel, Wylie became really insecure and needy - so I felt terrible for him, like he felt "wasn't I good enough for you?". Oh, the guilt. Now, they are BEST buds - so adorable together, wrestling, teasing, bone wars, chasing.
The only thing that sucked was Wylie was FINALLY potty trained (after, ahem, about 1.5-2 years!!), and then we had to go back to an untrained puppy. But, no - I don't regret it! I love my boys.