Had this thing that became an argument, any suggestions on how to deal with this in the future would be appreciated.

GF is staying at mine, it's late and I finally come into the bedroom after doing some work and showering. I put on a shirt, get into bed. GF has been on the bed scrolling Instagram. Once I get into bed and get under the covers, GF starts undressing. She asks me to get her a sleeping t-shirt.

Now, when she asks me, I am comfortably under the covers. I would have to get out of the bed like an errand boy to get her shirt. I don't want to do that. My GF is standing by the bed, she knows where I have my shirts, she's gotten shirts before and nothing is stopping her from doing that again.

I say no, I'm tired, I tell her she's standing and is closer to my closet anyway. She keeps insisting that I get her the shirt. I recognize this as a shit test. At this point I'm fucking tired in general and tired of this shit. I slap her ass playfully and push her towards the closet. She resists and jumps into bed and gets under the covers and says "well now I'm in bed and I'm cold so you need to get me a shirt" etc etc. I keep telling her to go get it - I honestly had no clever comeback or wtv at that moment to direct the growing tension over this ordeal. We already had sex earlier and I really just wanted to sleep. I definitely did not detect any sexual undertone here despite her behind half naked, and I didn't want any sex and just wanted to pass out.

As this goes on, she goes from asking me with nicely to becoming more serious and asking me why I wouldn't just "do this little thing" for her. I laugh in her face, tell her how absurd this is since she's making this tiny thing into a big thing. She gets more upset. Finally, she went and got herself a shirt. She gives me the silent treatment (I wasn't trying to talk to her, but you can always feel the silent treatment) and I pass out without us making up.

Anyway, I'm not sure how I should've dealt with this. Any criticisms here are welcome.