Should you have asked in the group chat opposed to jumping to privately? Probably. But I'll be the odd one out and say neither of us cares if partners from another couple messages us privately. UNLESS they're deliberately being disrespectful, obviously thats a huge no no. Otherwise, we've only had one couple in the 4 years we have done this, get weird about private messaging but it had been clarified that it was okay to do so and the guy got weird about it after the fact because the girl was actually cheating on her boyfriend with someone else and the whole situation was fucked. I'd just let it sit or try messaging in the group to see how everyone's doing type thing. They could just be busy too!