As a husband, there are so many positive ways that a comment like that can be taken, and there are so many implications. It could be in a literal, emotional, spiritual or even physical sense. No matter how it plays out, it requires first that I notice that her glass is empty (or nearing emptiness). To do that, I have to be paying close attention to her and to be able to see or even anticipate her needs before they become too great. In the most literal sense, it would be great to offer her refreshment before she becomes thirsty. But it’s not different in any of the other scenarios either. If I’m paying attention, I can see that she is getting nervous before she panics. She is upset before she’s enraged, or that she needs some intimacy (by her definition) before she grows cold.
Noticing it is the crucial first step, but then it is important to proactively do something about it. In our 30+ years of marriage there have been times when I have noticed needs (an emptying glass), but have been too self-focused or busy to do anything about it. You get no points for diagnosis if you don’t follow up with a remedy. It doesn’t mean you have to reorganize your entire day or drop whatever you are doing to pay hours of attention to your wife. But it is important to stop, notice the emptying glass and take the time to refill it. I’ll never know if that waitress was simply suggesting that I get my wife another drink, or if she was pointing me toward a far more profound learning. In either case, it was a great reminder.