I've been guilty of not replying to things like this - and not because I am being rude but because when I've gotten a text I've not known at the time whether I can (or want to come) and then forgotten about the text in my inbox and forgotten to go back to it, or I've been toddler wrangling or at the shops or out and just can physically respond and forget later. Other times, frankly I have been too busy, balancing work/a child/husband/family/home commitments and trying to find time for myself I often forget things. Don't judge someone so harshly just because they forgot to reply to an sms However if someone rang me and asked me personally, generally you'd get an immediate response from me, as then you have my full attention

I guess its a sign of how we do things now - sending what will seem to some (an impersonal invite) via text or facebook is easy to be overlooked by the recipient when they mean to reply to it later, but never get to it.

For Weddings/Parties the done thing is to send an actual invite in the mail, a bit harder to forget to respond too (I normally stick them to the fridge so they are in my face), however a text invite is easily lost in an inbox full of other texts IYKWIM? I do agree that its quite rude not to respond by the RSVP date when you have a written invite to something.