To >>61
You forgot mentioning 12 and 22.
I totally agree with >>65. They are my own guidelines where things are most likely to work (and add a little of ethics). You could think 17 and 12 could never work... or 25 and 15. or 12 and 22. I dunno since I'm older now. Just use your brain, and measure up the situation... sometimes the situation allows for such large discrepancies; most of the times it doesn't. >>65 sums up my conclusion as well.
And as >>62 does, he's 22 and gf is 15. Works I s'pose.