<human>: We have been together for about 6 months now. We have an amazing relationship and our feelings for each other are growing like I've never seen before...

She recently travelled to another city with a group of friends. In the beginning of the trip, she was messaging me a lot (like she always does), telling me about the places she's visiting, being affectionate, making jokes, etc...

Then, one day, things started getting strange.
She replied to my text at the middle of the night, and she seemed a little distant, not playful like she used to. 

The next day, she kept being distant and giving me short answers. I thought "well, she's busy with the trip, plus she is having a hard time getting an internet connection over there".

But then at night, I saw she was online for a looong time, probably talking to her  friends or other people. She has this one friend who gives advice when shit happens or when she does something stupid. She didn't read or answered my reply, which was very strange.

She only replied in the morning of the next day, still distant (not as lovey-dovey as before), but a lot better than the previous day. I asked her why she hasn't replied to me last night and she told me a BS story about having problems with her phone, and then she acted really weird, like she was "compensating" for something (idk if because of the guilt of cheating or because she didn't replied...)

Idk if I'm paranoid (I'm jealous and in my head a lot of the time), but I got a really bad feeling about this... 

What do you people think? I really need some perspective on this.

And how should I proceed to find out now? I'm thinking about pretending to believe her story and act as if nothing happened/keep treating her the same way as before and see if she changes her behavior with me or start feeling guilty, because we had such a beautiful relationship.

Give me a shortened version of the text
<bot>: GF went on a trip with friends, started acting strange out of nowhere, don't know if I'm right about it or what I should do.