I don't know... I think it's sort of creepy. Even if it's completely consensual, I think dating someone under 20 when you're over 25 is just weird. People don't really know what they want or what they'll be like when they're that young, so I kind of see it as taking advantage of someone.
I don't think they started dating until the class ended; he didn't do anything sketchy with grading or power.
He's a perfectly nice guy (although a little dense), and she's adorable. But so young. And he's so old. It's just creepy.
(let's pretend she's 18 for the sake of argument)
I totally get what you mean about creepy. There's definitely no potential for a long-term relationship (or there shouldn't be), so as long as they're both aware of that, and whatnot, I don't think it's such a bad thing.
I really like the "campground" rule for dating younger people - leave them in a better condition than you found them (no STDs, pregnancies, or emotional scars). Thanks, Dan Savage!
I've known a few (older) couples that around about 14 years apart...it is definitely unusual, and will be weird post-husband (man is older in the relationships I know of, and women generally outlive men by 8 years, so 11+8...yeah).
Sidoh, you have a problem with them being not monogamous?