Had to cancel and now she won't talk to me

Just carry on like it didn't happen. She can't expect you to leave the day free when she hasn't messaged you for 12 hours.

Wait it out. She’s probably a little annoyed however she should be understanding. If she’s being that petty over that then you deserve better

Well that is what I was thinking, and surely she can't be angry at me cancelling when I had a genuine serious reason why I had to cancel.

you didn't even cancel, you hadn't made any plans... what does she expect, that you say no to everyone and sit around the house alone? because she could well have messaged at 11pm to say she was busy or something had come up or even that she was just a bit tired

sounds like she's bad at replying in general so I wouldn't think too much of it and don't make a thing of it because if she is angry then acting like there's a problem will make her feel like she's right to be angry - act like everything is fine because it should be

I was thinking about seeing if she wants to do something this weekend. Should I just ask her and not even mention what happened last week?

Last Friday morning I messaged this girl I've been seeing to ask if she had any plans for the following day. She messaged me back around 3 hours later saying no she didn't so I replied "do you want to do something tomorrow?" I then saw that she had read the message but didn't reply (this was at about 11:30am).

She then messaged me back at nearly 11pm on Friday asking what I had in mind. However, in that 12 hour gap my pregnant sister rang me and asked if I could take her to the hospital on Saturday for her baby scan as her husband got called into work and no one else could take her. Obviously I didn't want her to go on her own so I agreed to take her. I then messaged the girl back being really apologetic saying I was now busy on Saturday and told her why and asked if we could maybe do something this weekend instead.

However, she has read the message and not messaged me back. What should I do?

maybe she thinks you're a flake and are just BS-ing her around..

I know one or two people who are usually all set for going out, then as the time draws near you get radio silence from them and then some lame excuse about family emergency or something .....and you just KNOW it's absolute bull............