This (within reason and legality obviously)

It's a case by case thing. Admittedly I'm defending myself here as I'm 41 dating 25 and I will never assume to be a good person or doing the right thing but am at least trying. Basically minding and respecting the gap but allowing the fact we fell in love to go ahead and happen.

• Both guys (idk, I heard age gaps are more common with gays anyway?)
• He was the one to approach me and ask me out, I'd thought about it but was reluctant to, turned out he got there first
• I check regularly that he's happy and remind him of where the difference will be in 9 years for example
• It's an open relationship, largely for his benefit and freedom (of course I get some fun too) and heck we're not actually all that sexual between ourselves
• I'm not in any rush to pin him down, and often say he's free to do what he wants, enjoy the 20s fully and decide for himself if he wants a future with me or not. If one day he finds someone closer in terms of age or distance and wants to let me go, of course I'll be heartbroken but love and want the best for him so would respect the decision - hopefully ultimately remaining friends and lives made richer than when we started.
• To be honest, whilst I know it's not a good thing, I'm a late bloomer, so in various ways kind of like the same age but sadly in an older body

I'm not gonna be like "oh I'm a good person so it's fine", I don't know that. I might be an asshole. I can only try, based on things like the above, hopefully without being labelled something nasty.

(Who am I defending against anyway? Probably my own conscience.)