It’s an okay guideline. According to that rule the youngest I should go is 29 45/2 = 22.5 + 7 = 29.5 so round to 29, but people don’t change much between 25 and 49, so fuck it. But my old fwb was 18 the first time we hooked up, so I guess I broke it already Fwb is different than dating though. I don’t think I’ve ever broken the rule with someone I dated. My last ex was 35 when we got together, one before that was only 2 years difference.