Not expecting them to reply immediately, but for instance a friend had a baby a few months ago. I messaged asking how he's doing, with no reply and it's been 4 days. I know having a baby takes up a lot of time but she's often posting on social media and online, and has a lot of support from husband and family so I'm not sure why..
The second one is an old colleague/friend. I asked him if he and his partner would be free to meet up with my partner and I anytime between x and x date as we would be in their area.
No reply and it's been several days, even though he had replied to previous messages.
Just makes you feel a bit awkward like have I said something weird or annoying, though I don't think so. I don't constantly message them either