that's because each red myrs venom is unique to them and they are immune to their own venom so while they can get off on another's venom they won't for their own. This also applies to characters in game in terms of why you can't do that. See Charmaine myr venom scene as an example:
( “I was just wanting to share a kiss.” You run your rough tongue over your lips for emphasis, wetting them with a glossy sheen of your aphrodisiac-laced saliva.
The lizard snorts derisively, planting both hands on your supple, handful of ass and squeezing hard enough to force a whimper past your moist lips. “You’re fucking weird, Sylvia,” he growls, “But fine, whatever...” He grudgingly lowers his bestial face close to you once more.
His black, canine-esque tongue shoots out of his maw, the incredibly soft muscle slapping against your lust coated lips as he gives your muzzle a curt lick. He retreats before you can even gasp, a smirk on his snout as he licks his chops and takes in your taste.
“That’s all you’re getting,” he states matter-of-factly, “I don’t know if you get off to that at all, but I don’t... Even if you do taste pretty good...” His body abruptly blooms with heat, nostrils flaring in agitation and alarm. Barely a moment later, though, he grunts out an “Umph!” as you feel his monstrous shaft bolt to full mast against your loins, the ribbed length flexing and pulsing urgently.
“Are you sure?” you moan as you are pressed against his hot, solid form, taking the chance to run your tongue along a thick scale girding his muscular chest. You have no idea if your venom even affects him through his scales, but it seems to encourage the lizard nonetheless.)
and sylvies:
(“You know, there’s another story I could tell you about my travels. Well, this is more of a show than a tell. I visited this planet full of ant girls, and some of them had the most delicious aphrodisiac venom ever. So delicious, in fact, that I just couldn’t leave without sharing in such a wonderful trait,” you explain. Sylvie nods obliviously, but that’s alright, the explanation was for nothing but dramatic effect. As you finish speaking you move her hand from your cheek to your luminous silver lips, sucking one finger and lavishing it with oral attention.
A shuddering impulse travels up her arm, and you revel in the sight of your venom’s effects on the off duty officer. Her eyes dilate intensely, barely managing to stay focused on you as the aphrodisiac spreads in her body. Barely contained breasts shudder as her breaths become ragged, and her tauric legs begin to fidget and trot in place. The fluffy brush of her tail juts into the air, the last inch of her body to fall under your spell.)
your character doesn't feel anything from their own venom otherwise the moment you got the trait you would be instantly addicted to it.