Hey, I'm a 40 year old bloke, not had to use condoms in a long while as been with DP for 17 years. I apologise in advance if I'm about to get a bit TMI.
Erections are not the same at 40 as they were in my 20s, or even my 30s. When you're 20, the smallest little thing sets you off. Woman lying in bed stroking my chest, erection. The mention of sexy time later, erection. And once you're up, you're up for a good long while. (To the extent that sometimes it's really annoying and inconvenient)
By the time you're 40, things aren't on a hair trigger so much. I need hands on junk these days before I get hard, whereas before I could start playing with DP and the erection would sort itself out. And I can't necessarily rely on it for the duration any more either. If someone stops for a water break, or to get the lube out, or has a coughing fit, or any of the other funny or awkward things that interrupt a sex session happen, then I may not be as hard as I was when we resume. Hell, even a position change comes with a slight risk.
I don't know the solution for the condoms, as I said I've not needed to use one for over a decade. But my weight and overall fitness level make a difference to my erection, as does how frequently I masturbate. I'd imagine that foreplay, condom, a bit more foreplay, then sex would probably help at all. Also having the condom chat before anything even starts, rather than when things have already gotten a bit hot and heavy.
None of the above is to say that it's OK for men to be making you feel awkward for wanting to use a condom. Condoms should be the expectation, rather than the exception when it comes to sex with someone new. This is the man's problem to solve, not yours.