>It's reasonable to think that the potential for exploitation in such relationships is higher than if the younger party was 25.

If a 45-year-old want to risk being exploited by women (of 19 or 25), who are you to tell him otherwise?

By a malicious standard, even a GL spending a day pushing a little girl on a swing, carrying her on his back and buying her the occasional ice-cream is "exploited", despite probably loving every moment. Are both "exploited", despite being happy, because it fails to meet the arbitrary standard of a malicious third party?