Turning down invites: do you give a reason?

[happyclappy123]

Just want a variety of opinions on this. I have a friend who if I imessage her an invite to something and she can't make it just says no, without any explanation or apology. I on the otherhand would always say no, sorry can't because ... maybe another time. I thought that we just had different styles but today I got turned down by 3 people, one of whom was this friend who just said no can't make it whlie the other 2 gave reasons. Is my friend just rude or is this normal behaviour?

"Sorry I can't make it" type response is fine.
A single word "no" would come across as rude, but I don't expect someone to justify to me why they can't come to something.
As Emma said on P1 - it does depend a bit on the occasion.... a last minute meet up for a drink is very different from not coming to the wedding of best friend of 30 years - for that, I think I would like the person to explain why, but if it were a colleague I'd invited to a wedding, then it would be fine if they said "Sorry, not able to come, hope you have a lovely time" without telling me why they weren't coming.