Friend is suddenly ignoring me

I've had a pen pal based friendship with 'Steve' for about 7 years now - we live far apart and we email each other once a month or so, and meet up when we are both in town from university/jobs. We last emailed in late April because Steve was going on a big European holiday and I was moving house in late May/early June so it got a bit hectic.

We also have another friend 'Dave' - Dave was more of Steve's friend originally and they are still closer than I am to either of them but I speak to Dave sometimes.

I emailed Steve 2 weeks ago to ask to meet up. He hasn't replied which is quite out of character. I messaged Dave and he said he'd seen Steve the month before and Steve's partner was sick but she was better now and Steve seems fine. Dave suggested I make a WhatsApp group with all 3 of us to organise a catch up while we are all in town, so I did. Dave replied in it and Steve read the messages but hasn't responded in over a day. He still hasn't replied to my email and I'm quite an anxious person so I'm spiralling. I can't have done anything except for not reply since late April but this is totally normal for us - we are the kind of friends who talk a few times per year and it's totally fine. I explained this in my email in July and we've gone for longer without talking before.

Shall I just give up? Shall I ask Dave to message Steve? I'm worried his partner is sick again but it seems weird that he wouldn't even send a short message to explain. I feel like an awful friend but I also know I've done nothing wrong. I just don't want our friendship to end but I don't want to bother him.