You lie outright

"What on earth are you talking about, Jacob? What message?" you demand, feigning puzzlement.

"This... you sent..." you hear him hesitate, no doubt reconsidering the wisdom of admitting to his girlfriend that someone sent him a dirty message. "You didn't send me a message just now?"

"I..." you pause, not wanting to outright lie to him. Though you've sometimes misled, avoided, or pretended to misunderstand you've always tried to be honest. But the desperation compels you, and you hear yourself saying, "Of course not! I haven't sent anything to you."

"Oh... It had your name on it..."

"Well whatever it was it was fake. Probably some hacker faking my ID or a friend of yours playing a prank."

"Right... of course," he says faintly. You can't tell if he believes you or not, but his next words make you think he probably does. "Will you... would you like... to come over tonight?"

Leaning your head into the oily mess you feel it soaking into the last remaining dry strands of hair and wonder if you could stand to look him in the eyes tonight. You don't really want to, but maybe you owe it to him. Besides, you've already broken a cardinal rule by blatantly lying to him, could you compromise your morals more by lying again?