This is cringey as fuck, but here goes:
One time I was on a flight and my GF was too, but we were in different seats. This was back when Priceline actually got you cheap flights (they suck now) and we had two different seats because Priceline.
I was totally hitting it off with the girl who was seated next to me. Really vibing with her.
When the plane landed, it hit me that she might be DTF. But instead of smoothly getting her number while she was sitting next to me, I didn't shoot my shot until the plane landed.
So she's walking off the plane, and my girlfriend is behind me on the plane, and then I run after the girl I was flirting with and I scribble my phone number down on a napkin and give it to her. Just so fucking awkward, because she was already well off the plane, AND my girlfriend was stuck on the plane and I looked like a complete cunt because I didn't wait for her, didn't help her with her luggage and TRIED TO GET MY DICK WET right in front of her.
Of course, some women are doormats and she never said a word about it.
Also, duh, the girl never called me.
EDIT:
I felt like a complete douche that day, and felt bad for how I treated my girlfriend. But it just occurred to me that literally every girl I've ever dated, there have been nights where we went to a bar or a nightclub and I came out of the bathroom to find that some guy was trying to fuck her. So maybe women are more tolerant of this than I considered.