Hi y'all, I just had a situation where two friends got mad at me for not inviting them to hangout, today on Easter, with other people from our friend group.

Here is some context:

We are all in a friend group of 5ish, I have known the people I invited for 4+ years, I have known the girls I didn't invite for about 2 years, only recently this year have we had more of a friendship the two not invited girls are best friends and have been for a really long time and they hangout without us, one really doesn't like big group social events.

Alright, so yesterday me(F19) and my friend, H(M18), decided to spontaneously have a hangout at a mall, then we decided to invite our other friend M(F19). While shopping we got a text in the group chat, from another friend, O(F19), they said "so we at (store name)" , later they told me O found out because O's boyfriend was in the same store, we didn't recognize him. Then I asked where O was, they said "where ever the invite is", my other friend, G(F19) said that there was obvious fakeness going on, and that an invite would have been nice and they could have gone if they knew about it sooner.
Was it rude to not invite them? I personally do not mind if I am excluded from friend hangouts, I'd just be glad that my friends are hanging out and becoming better friends with each other because I introduced everybody in the friend group to each other. Furthermore the two people I didn't invite are besties bro, I understand when they hangout with each other and not include me, so I would expect the same with my other friends too. But I am just wondering is it expected to invite everybody every single time? Because I don't really want to invite everybody every time and it really isn't that big of a deal to me. The two said that hanging out in a trio and not inviting the rest is different from hanging out in a duo and it is a big deal to them. I just don't know how i'd go about making hangouts in the future if I had to make group hangouts every time. This plan was made a night before. I would love to hang out with those two friends but it was so last minute and it was Easter I didn't think to ask what they were doing, but whenever I told them that they were not very accepting or understanding and insist on everybody being invited to hangouts.