Hi Celery, are they in the same cage, or separate?
@Zara has multiple and may have some words of wisdom.
In general, if you only had Kermit for a week, any bond is still forming and delicate, so significant changes can disrupt that.
Spending less time together, having the daily schedule changed, the addition of a new bird (especially if placed in the same cage), will all cause stress, and a stressed bird is a defensive bird. If you were having success bonding with Kermit before the new bird was added, consider what changes can be reversed.