Hey! I'm a 21 year-old man who's been in a relationship for about 3 years with a 22 year-old woman.

We met 5 years ago online through a joint work effort (website moderators) and we quickly become best friends, until we both admitted that we were crushing on each other. This was made official three years ago when we met face to face and decided that yeah, we're right for each other. The anniversary of our first kiss was in fact ten days ago.

Now here's the thing... My GF and I live in different countries; I live in Norway, she lives in England. We both come visit each other frequently (several times a year, sometimes for a month or two) and I would say that we know each other very well by now.
However...

I'm on visit with her right now and I'm a bit confused. I'll be the first to admit that I'm not good at reading people, and she knows that. I'm not good at analyzing what people say or figuring out what the proper response is to certain situations.

When we're together, we always make sure to kiss each other good night but last night she didn't appear that interested.
Being a person who relies on habit and predictability for comfort, I made a motion to kiss her and she didn't let me. She said she was unwell at the time so I nodded and did the respectful thing and let it be. If she doesn't want to, I'm not going to force her or confront her.

Thing is, we've promised to each other that we're always going to be honest to each other, no matter what, about anything that bothers us about each other 'cause we both know how relationships go if we're dishonest.
And I trust her to be honest; if she says she's unwell, she's unwell.

I'm just a little worried that she might be mad at me for something, and I don't have the self insight to tell if I've done something that could have made her mad at me. I shouldn't be worried, but because what happened wasn't routine, I grew a bit insecure.

I know perfectly well what I should do: ask her.
But our promise considered, I'm not sure how I could ask her without sounding like I didn't trust her answer from last night.

Advice?

Just say to her are you feeling better than you were last night and wait untll she answers. If she doesn't answer than say to he have I done something to hurt or to offend you. And then go from there and if she starts getting mad then just keave he alone for a while and then say sorry and then see what she says

Trust but verify, and be nice about it. Gentle but firm. 3 years of long distance is enough to stop anyone from wanting a perfunctory friendly kiss. Unless you are related.

Thanks for your suggestions. I did eventually ask if she were mad at me for some reason but all I got was a "dunno". I'm not really reassured but I'm guessing she'd have said it if she were so I'll settle with that.

Appreciate the help <3

Update: Seems the long distance relationship is taking its toll on us. Finally did get a proper conversation going and she doesn't feel the same anymore. It's just not there.

We're going to talk about what to do next as soon as she feels up to it. Hoping for the best, preparing for the worst.

Just ask once, if she gives you a direct answer then great, if she doesn't then it is on her. As far as why she is acting this way, maybe she has stress coming in from work, or school (not really sure what she does)... be patient, see what she has to say, maybe there is something in her mind that is bother her at this precise moment.