A slightly-differently-worded version of da "I wanna see what you get to experience all the time" justification could likely also suffice if you have a chance to be alone wif a
guy's alluringly-curvaceous-and-busty significant other and are asking her directly if she'll spread her legs for you; what you'd say instead when explaining why you're requesting intimacy wif her would be, "I wanna see what your husband/
boyfriend gets to experience all da time". And in fact, you very
well might even have a better chance of consent when you're just wif da
gal by herself than you would wif asking da
guy, since he would not even be present at dat time to be "doing it" wif her himself in da first place, and so it wouldn't even be as if he was missing a sexual opportunity of his own by her doing it wif you; you'd simply be "filling in for him" ---
literally, as in, "filling" da chick's
love-tunnel wif your
love-pipe --- during his absence. As soon as he gets back, he could likely start "doing da bouncy-bouncy" wif her immediately da way he usually could, regardless of her also having had sex wif you shortly beforehand (provided you didn't make her too sore "down there", of course --- use lube and
go easy on her so as not to make him suspect dat another
guy was luluing her).