Actually... I've been recently through sexual harassment training which explicitly said that asking another employee out, going with them for a weekend and making compliments is not harassment, unless either (1) the recipient unequivocally said "no" or (2) there's some quid-pro-quo involved such a promotions or pay raises.

So you've probably missed your chance to have a nice weekend.

I think GP's concern is legit, especially if the colleague was a subordinate, or could become a subordinate in the future.

Not only could the colleague bring a claim of harassment if things didn't go well, but other colleagues could as well — on the grounds that this female colleague received special treatment as a result of her relationship with GP.

Training videos aren't legal documents: they say one thing, but fine print says something different. What matters is how the rules are applied in practice. And the practice is that women are given the upper hand in nearly all situations. This means that if I took that offer and the colleague changed her mind a year later, the harassment rules wouldve been applied retroactively because it helps the company's image. And if they later found out she was lying, then the arbitration clause would apply that would bar me from seeking a legal action (which wouldn't fix my reputation regardless of outcome). This is why that opportunity was more like a cop asking "Hey, I'm in a good mood today, if you wanna test drive my police dodge, keys are on the table - just bring it back tomorrow morning."

Making compliments on physical appearance is considered harassment - especially if it is done repeatedly.

The OP absolutely did the right thing. Romantic fraternization should not be initiated in the workplace.

No, making unwanted complements on physical appearance is considered harassment. Knowing how to politely comment on someone's appearance is a learnable skill. (granted there's an assumption that certain kinds of comments on physical appearance are presumed unwanted, but I think that's reasonable.)

That's not correct. It is in fact just any comments. It's strange but true. I know because I just finished a D&I training recently.

That could be true in your jurisdiction. In general it isn't.[1]

[1] https://www.eeoc.gov/sexual-harassment

Let's agree that anyone who is concerned about workplace sexual harassment should do their own research and not rely on an internet forum for legal advice!

I think the point is that if your career (and life) were to be unexpectedly destroyed months or years down the line as a result of this (even if you were acting both in the spirit and within the letter of company regulations at the time), you would be in a strictly worse position than if it had never happened.

Good point. And my comment didn't add much but it's too late for me to delete it.