A couple go out on a first date to a very nice restaurant. They have a wonderful time. After the check is paid by the guy the woman goes to?

He just asked her out again. This time she told me she'd help figuring out the 20% tip or she'd just take care of it as her contribution to the dinner. Next time she'll ask him out. Thank you for your help. (this is my daughter)

Sounds like you're reaching for something to not like about this man. Some people tip terribly, it means they are cheap not horrible people, besides the service might have been terrible or the tip 15%. Honestly the idea of tippig the person who brings you water twice is ridicous to me, but whatever. Stop reading so much into every situation.

Nothing, for all you know the waiter is just a whiner. I mean I'd whine if my tip was not what I expected (i'd expect a high tip with little kiss up). But if it makes her more comfortable then she pays the tip or you both try to agree on a reasonable amount for the tip. Why let the voice of an outside person such as a waiter effect an important time with someone you are affectionate towards?

My first thought would be, what is the guys ethnic and/or national background? There are numerous cultures that tip very little or none at all.

I was once hosting a group of Italians and every time we'd go out they tip a dollar or two on a 100+ dollar tab. I learned to always keep a few 5's and 10's handy so I could tip the waitstaff on the sly.

Anyway, if that's the case then perhaps next time she should pay and make a obvious tip of 15%. Maybe ask him for help with the math to be more clear that 15% is the expected tip. But if it turns out the guy really is a total cheapskate, you might choose not to pursue any further relationship.