Girlfriend Furious After Sex Made Them Late to Board Game…

So I got invited to a boardgame club by a friend of mine, and I decided to bring my gf with (which he agreed to). About 1,5-2h before, we start getting ready. A bit later, she’s finished with her shower, she walks into the room naked and, honestly, I get pretty turned on. So I go up, start kissing her, and kneel to go down on her. She accepts this eagerly, and one thing leads to another and we end up having sex. Not like the “demons got into us and we idk what happened” sex, but some pretty hot but ultimately mutually consensual and regular sex.

As we’re done with that, she’s kinda quipping about how I get horny when we have to make it somewhere, and I’m like don’t worry, it’s no big deal, take as much time as you need and don’t rush, I’ll let the friend know we’re late and say it’s my fault, they’ll start without us and that’s that. She’s like – ok sure, and goes to keep getting ready. At that point we still have about 50 mins left until the arranged time, but I assumed she’d need longer so I immediately call in that we’ll be late.

Now comes the plot twist – another friend Y is also late and so he’s offering to drive us there. I tell my gf that, but minding not to put any pressure on her, I’m like – hey, Y can drive us, he’ll also be late so we can basically tell him to come whenever, or we can just tell him to go alone. She’s like okay yeah thats good, and she gives me a time by which she’ll be done for sure, I let Y know and that’s that.

However, as that time is approaching, she starts getting more and more frustrated and pissed. She spends like 30 minutes trying to get her hair to look exactly the way she wants her to – like tying it, saying she looks r-word and hideous, letting it all down and retying it again, over and over. And I’m next to her, reassuring her, saying I think it really looks nice (honestly), even taking pics from different angles to show her it really looks fine and she’s overthinking it. But she’s just getting more mad, starts yelling how it’s all my fault, I fucked up her timing, she’ll lose the desire to have sex with me in the future because of this, it’s the last time she’s going somewhere with me, she even threw her armband at the floor at one point, how frustrated she was. All the while I’m trying to calm her down but am also flabbergasted at what’s happening.

At some point we finally leave, the Y friend waited a couple minutes extra for us but he smoked a cig and said its no biggie. The boardgame evening itself went great.

Afterwards, we come back, and I’m really feeling off about the whole thing. She asks me if I’m pissed, I say not exactly pissed but not feeling the happiest, but then she asks me “is it because of what I said to X” (something random she said during the evening), and I’m like, hell no, it’s because of the entire meltdown you had on me because I dared to be horny for you?

We ended up arguing, I made it very clear I find her reaction unacceptable and I felt awful about that, while her reasoning boiled down to “oh so now I can’t be frustrated about a valid reason”, and how I should basically learn to keep it in my pants when the timing isn’t right.

We kinda left it at that, and talked normally a bit after, but then I went to the room to sit on my PC and decompress a bit. About 15 minutes later I come back, see her studying, ask her something but she ignores me and doesn’t respond. So I went back to the room, and here I am writing this.

Long story but, am I really that dumb about relationship interactions that I’m missing something obvious here? How can I get past this?