I think if (and it’s just the smallest if in the world) your long term partner is one of these possibly mythical “posh wank” types, you’d already know he used them, without the situation of “discovering” a condom.
If (if if if) he was one of those posh wank unicorns, you’d have spent your marriage seeing boxes of condoms in your shopping basket and in your bedside drawer.
And you’d have seen the wrappers in your bin.
Especially if he’s Mr Zero Fucks Given now, so therefore not inclined to hide it.