Can't get this thing out of my head

Hey y'all, There's something that has been bothering me like crazy in the last two days; my girlfriend (19, I'm 20) left town for the weekend (education purposes) and she's been crashing at a friend of mine's place for three days. I'm not a possesive person, and I don't feel comfortable telling other people what to do, because I'd hate it if somebody did the same thing to me; but I feel like there's an underlying issue, here: lack of respect. She swore that she told me everything before leaving, but I couldn't recall the moment in which she said "hey, I'm gonna go sleep in a single man's appartment, and it's gonna be just the two of us". I think I would have rememberd something so peculiar. I feel weird, I mean, this whole thing feels hella weird. I would have never done something like this without confronting with my partner first. This is not a question of pure gelosy, I think the real issue is the fact that I feel cheated on. (in a non-sexual way) I've been kind of absent in the last month, for personal problems and study, I wouldn't be surprised if she did something like this to get my attention, but, man, this is not the right way to do that! Talking with your partner is the key to a geniune relatioship, and if you feel like there are problems, the only way to fix an issue is to talk it through together! Plus, the "host" is a friend of mine, she's never been that close to him, that's why I can't really get the decision of asking him to let her sleep at his place. What would you do? How would you feel about this, if it happened to you? We're not gonna meet until friday and I really needed to depressurize some valves before talking to her. (I don't like talking about serious matters via whatsapp or facebook, that's why I'm waiting to see her in person to discuss) Thanks in advance!

Depends how well she knows him, how many times they've met, etc. Sounds like it would have been more appropriate for you to ask him the favour, not her, because he's your friend. I think if she'd told you about the arrangement, ie; I'm staying at X's place, free accommodation and all that, you would have remembered. I'd probably be suspicious, but without knowing what sort of person your GF is it's hard to answer.

They don't know each other that much, I think they may have met four or five times before this all happened. She's usually very caring and considerate, that's what hit me the most... even though we've known each other for 5/6 months and I recon it's not enough to say you -know- what an individual is truly like.

I'm 100% sure she was there alone. You're sure right about the fact that we don't know each other well, but witholding informations is not the way to earn somebody's respect and trust. I found out that she was staying at my friend's because I asked her if she was there alone or if she knew somebody that could let her stay at his/her place for the time being. But yeah, only time will tell

If I was in your position I would be very suspicious. Hitting someone up for accommodation when you hardly know them is at best presumptuous, at worst something much more shifty. I could be way off the mark here, but I'd look into exactly what this 'educational' weekend is about. What exactly has she been learning, where exactly was it held, who delivered the lectures and the classes, what's the hosting venue, etc. Sounds to me like she's manipulated her way into your friends house. Whatever, asking YOUR friend to accommodate her without telling you is just really bad manners towards him and disrespectful towards you. I think she's up to no good.