There's no real "right" or "wrong" answer - it all depends on the gal. In my case, I could never tell my wife. She would be disgusted & think I was shallow, & ask me why I thought something was "wrong" with my penis, etc., etc. And, I'm sure she'd blab it to her sister, who'd tell her husband & her mother, and her mother would tell her aunts, who would tease me about it, etc., etc.
To hell with that. I let the wife bring it up to me - and she has. She flat-out asked me, "What's up with your penis?" When I asked why, she said sex was becomming uncomfortable & she wanted to use a lubricant. I made up a million excuses - she's just getting older, my kegel exercises (to aid my erections, which were becomming softer) were to "blame," blah, blah, blah.
Oh well, she bought it - for now anyway.