Cultural differences or overstepping: female friendships?

TL;DR: the new guy I’m seeing has a lot of female friends and it’s making me feel insecure about our connection. Could it be a cultural divide?

Is this weird or am I overthinking?
I’m (27F, American) visiting a guy (30M, Austrian) I’m seeing (we’re not official, but there’s mutual romantic interest and history). We’re reconnecting in person after our initial meeting in May. Since that meeting, we’ve been in consistent communication, he’s told his friends and family about me, and has continually made his interest in my clear. In fact, I’ll be meeting his friends and family when I visit soon. See original post here about our initial meeting (idk how to tag it it’s the only other post on my profile).

I’ve seen no red flags thus far except for this one thing that has irked me. I’ve begun to question how many female friends he has and want to know if you think this could possibly be a cultural divide or what. Any advice/thoughts appreciated. For context, I’ve provided a few examples of situations I find a bit strange:

1. He casually mentioned to me that he had a friend coming over the night before I arrive to help distract him and his nerves. It’s a female friend, who not only has a boyfriend, but he expressed a dislike for her boyfriend… hmm. From what I can tell, she’s cute, friendly, and they seem close. He mentioned that she is the ex of one of his good friends… He didn’t hide that she was coming over or anything, but something about it felt off. For me, if I were her boyfriend and she was having essentially a date night with her “close male friend” at his apartment on a Wednesday night… I would be suspicious? It also begs the question: if he and I were to have a disagreement in our relationship, is that something he would feel comfortable sharing with this female friend? She has opened up to him about arguments in her own relationship? I’m not worried they’re hooking up, but I can’t shake the feeling that having a cozy dinner alone with another woman—right before seeing someone you have romantic tension with—feels a little emotionally tone-deaf? Even if it’s innocent, the timing and intimacy of it unsettled me.
2. Another example: while he was in my city, he was casually spending time with one of his male friend’s girlfriends. Which I found weird, although no one else in the situation seemed to mind. They went on long runs together and she showed him around the city. Again, I don’t think there was any tension there but kind of odd. If we were in a relationship, I wouldn’t be comfortable with him spending that amount of time alone with another woman on his Saturday afternoon..
3. He went to one of his BEST girl friend’s weddings and bought a brand new outfit and wanted to “look good for her.” Again, clearly this person is fully getting married – I don’t think he is interested in her. But why would he say that to me?
4. He is still in casual contact with his exes. I understand many people do this. Is this common in Austria? Personally, I do not speak to my exes as I want to make room for a current or future partner rather than keeping a broken connection alive. Sure, I’ve stayed in contact with exes before… and when they get into a new relationship they usually tell me and we cut contact out of respect.

All of this to say, I am self aware enough to know that I lean towards the jealous side. But I still can’t help but feel some of these feelings are valid. Sure, the thing with his friend’s wedding and him looking good for her – that’s nothing. But an apartment dinner date with a girl who has a boyfriend you don’t like right before I come into town?

Side note: For me, the only male friends I have are friends I’ve had since childhood or they are gay. Otherwise, almost every adult male friendship I’ve had has turned into them trying to pursue me romantically (which I’ve never been interested in). I guess that’s my other perspective: all the guys I know that have “been my friend” only did it under the guise of later pursuing me. So that’s why I wonder… is that what he is doing with his “best girl friends”?

Am I being insecure, or would any of this rub others the wrong way too?

On the flip side of the coin, maybe he is a really good guy who doesn’t objectify women and views them as actual humans. Which is wonderful if true. But at the risk of sounding controlling, if I were in a relationship with him he sure as hell wouldn’t be spending his Wednesday night eating dinner in his apartment with another girl?? Likeee??? How did he think that would sound to me??