AITAH for accidentally turning what might've been a date into a group hangout?

I (24F) have a former coworker (26M), I'll call him K. We became friends through work and started hanging out every now and then, sometimes with our work friend group and sometimes just the two of us.

The first time we actually hung out alone he spent most of the time talking about problems with his fiancée, they were trying to work things out, and eventually they broke up. I mostly just listened and gave advice when asked and I genuinely only ever saw him as a friend.

After maybe 2 hangouts (just us two) he started making comments that felt a little flirty (complimenting my smile, saying he missed seeing me, etc.), but I honestly didn't think much of it because he was still dealing with everything with his ex and never actually said he liked me or anything.

One thing that always confused me was that he'd be really talkative for a while, then disappear for weeks or even months.

For example, one time we made plans, he rescheduled twice because of work, then just... disappeared... no text, no explanation, nothing. Later the friend group decided to meet one day, he texted me asking if I was going to the group outing, I said I couldn't make it -I wasn't doing great mentally at the time- and then we didn't talk again for another few weeks.

A couple of days ago he texted me asking if I'd seen a movie and if I wanted to go watch it with him. I said yes.

On the day we were supposed to meet, another mutual friend (Z), who's known K for years, asked if I wanted to hang out earlier that day. I thought it'd be nice if all three of us met up before the movie, so Z texted K asking if he wanted to join us.

I texted K too. He replied saying Z had already messaged him and that where we were was too far.

So we suggested another place that was much closer to him.

This is where it got weird.

He ignored my calls completely, but answered Z's and he agreed to meet us at the new location.

When we got there, I texted him asking if he was coming. He ignored me again.

About 10 minutes later, he texted Z (not me) saying he was feeling too lazy to go out after all.

He never replied to me throughout this exchange

I know I should've asked him before inviting someone else since he was the one who originally invited me. If he wanted to catch up one-on-one, I can understand why changing the plans without asking might've annoyed him.

at the same time I also feel like ignoring my calls and messages while only communicating through our mutual friend was pretty rude.

part of me is wondering if he thought it was a date while I genuinely thought we were just hanging out as friends. We'd hung out one-on-one before, but we'd also hung out in groups plenty of times, and he never actually told me he was interested, so I didn't think inviting another friend would be a big deal.

I'm mostly posting because I want an outside perspective, i was thinking of sending a text to try clear things over but i'm conflicted about it

so... AITA? and what should i do next?