I have a good friend, A. I met her through our kids school, though the kids themselves are not in the same year (primary). They have some common interests and spend some time together through circumstance but are not really friends.
There is another mum friend, B, that we are very loosely friendly with. A and B’s kids are in the same class. Her child also has a common interest with and spends some time with our kids but again they’re not really friends. This child is having a birthday party and invited my child but not A’s child. No rancour, B was limited with numbers and birthday child chose my child to invite, so we’re going.
A doesn’t know about the party. Should I tell her? I didn’t initially as it’s not my party and she would feel left out for herself and her kid and I don’t want to hurt her pointlessly. But it feels very strange to deliberately keep things from her. I keep in touch with A almost every day and we share a lot things going on in our everyday lives, though not every single detail - so I have no idea what she and her kid are doing that day, though we would probably catch up soon after. We lean on each other a lot for support.
Also I think the chance she would find out about the party is very low (if we weren’t invited then I would have no idea either) but it’s not zero.