How to deal with an awkward situation with someone I'm not close to

Hello,

I am currently in a dilemma with someone I'm not really close to. So in high school, I met two people (person A and person B), and we became friends. After we graduated, we tried to keep in contact with each other but naturally our busy schedules got in the way since we all went to different schools. At the end throughout the years, I mostly ended up staying in contact more with person A just because our personalities matched well and we ended up surprisingly being able to talk day to day without any issue, while with person B we ended up only texting on random holidays and birthdays, and just check-ups 1-2 times a year. It wasn't on purpose or anything, just happened naturally I think.

So overall, I can call person A a close friend confidently, but with person B it's more like someone I was friends with in high school and someone I text on birthdays, if you know what I mean - just a friendship that naturally grew apart. The thing is, person A and I planned a trip together since we're close (person A and person B had the same growing apart issue that I did with them btw). And we posted pics on social media like normal, but then person B asked us out of the blue why we didn't invite them.

And I just feel awkward because I don't really consider us actual close friends anymore because we barely talk to each other in the past few years (the last time I spoke to them was last year, and that was only a few texts), but then I feel bad because in high school we were a trio. So I'm not sure how to navigate this situation. When you look at this objectively, am I (and person A) excluding them? Or is this a natural situation, and if so does anyone have advice?