Is there a problem with the values of this girl?

Is there a problem with the values of this girl, or is it something that girls will do but just not openly admit?

Lets call this girl Z. Z is not in any exclusive and commited relationship, recently just broke up with her bf, and in a complicated relationship with another guy.

So she decides to go for a solo trip, and in the trip she joins a small group of tourists and spends the next 2 weeks together. Just the 5 of them.

They get on pretty well, all about 20s to 30s. all single. She gets pretty close to them and maybe a little closer to one of them, though nothing romantic.

And one night after quite a bit of drinks, the group eggs the 2 of them to kiss and make out. And they did. and what follows is a steamy night in the guys room, just the 2 of them.

Now the thing is, both of them are from different continents, and are fully aware they will not be together, and have known each other for only a few days.

After the incident, Z feels that its a normal encounter, nothing to be alarmed about.

Is this a little frivolous? Too casual? Or is this something that girls openly or secretly will do and think its ok? Can Z be trusted in a long term relationship?

To add on:
Where i come from, if a girl was to tell this to her friends what happened, most of them will be shocked at the casualness of it. Maybe the guys will secretly be thinking its ok, but the girls will express shock and maybe show that this is beyond their moral boundaries. But secretly, do the girls think its ok, and will most of them do it if presented with an opportunity like that.

For a young woman to have brief encounters is quite normal, if it's a 'stage' in her life, say a couple of years casual dating in her twenties. Especially whilst traveling or at university etc.
If she does this all the time for a decade then it's something else all together, frivolous and dirty.

This is a normal thing to do for anyone, from anywhere. Yes, it's casual, but it's perfectly acceptable for consenting adults to engage in sex without the commitment of a relationship. It's not dirty. Men do this for years, sometimes decades or their whole adult life, and it's not called a "phase" lol. Some people don't want to be restricted to one committed relationship. If that offends you or turns you off, then find someone who is into monogamy.

alright.. The real reason i'm feeling upset is because i'm the guy thats in the complicated relationship with her. Shan't go into details here but we're working things out. We love each other, but given the circumstance, cant get together, yet, or ever, we dont know.
And the way she told me about the incident goes something like "Hey, i just had my summer fling! haha" like she was telling it to a girlfriend or a friend. I ask her whats a summer fling and she even grabbed the definition offf the net and show me.
What does that mean? Am i entitled to be upset about it?

Are you the boyfriend she just broke up with or the guy in the complicated relationship with the female subject?

I think the reason she told you might be so that you get jealous.. either that or you are miles deep in the friend zone. But if you were in the friend zone she'd have told you more explicit details, at least concerning her emotions about it , like "I like about him.." or "I know we won't meet again but I just needed it..." etc.

If you don't want her to see others ask her to be your gf.

Lots of single girls and guys for that matter have one night stands and don't think on this person afterwards...of course this girl could maintain a relationship when she is ready one thing doesn't knock out the other.

You say it's complicated, but I feel it's only complicated to YOU because you have strong feelings towards her. The problem is that her words do not match her behavior. Get the hint if she was really into having a relationship with you she wouldn't be having a romp with some random guy. She's been stringing you along and you are being a fool clinging onto hope. open your eyes bro! You can be pissed all you want, still doesn't change the fact she isn't that into you. I feel she is just using you because you have a weakness for her.