Tom was somewhat taken aback by Melissa's fowardness, but the bulge in his pants felt like every movement was going to set him off. He struggled to resist the urge to leap onto his girlfriend and mount her there in the hall. Melissa's shoulder length hair shifted strangely as if something had twitched beneath it. She gave him another slightly bucktoothed smile and drew herself close to him.
"I've just been really missing you today", she said, running her fingers down his chest and across his stomach, then further to caress his so sensitive member. Tom had to stifle a groan. Melissa took him by the hand and led him up the stairs.
As his girlfriend frog-marched Tom up the stairs to their bedroom, he took another moment to check her out from behind. 'Has her arse got bigger?' Tom thought. Melissa had always been incredibly slender, almost elfin. It was one of the things that had first attracted him to her. No matter what she ate in the three years that they had been dating had she ever seemed to put on weight. But now, as Tom watched his once slim girlfriend bound her way up the stairs, the seat of her jogging bottoms strained to contain the round cheeks of her fat butt. Her hips too seemed wider. They made her rump quiver as she saunted upstairs, one leg after the other.
Tom couldn't help himself.
He reached out and grabbed her arse cheek and squeezed. If she had put on weight, he couldn't say he minded. Her arse felt incredible. H couldn't but wonder how good it would feel fucking her from behind. Melissa giggled coquettishly and pulled her hand from his, placing it upon his hand on her rump, holding it there.
After what felt like an age, they reached the bedroom. Tom had just enough time to register that Melissa must have left the light on before they fell onto the bed, a tangle of limbs and wet kisses. Melissa seemed so keen she was positively bouncing on Tom's cock, driving him wild. He let out a loud snort from his nostrils, ripped her shirt clean in two, and buried his face in her chest.
Her bra felt weird. Like each cup had been covered in fur. But Tom was beyond caring. All he could think of was tearing Melissa free of her clothes and rutting, mating, fucking Melissa until her her belly swelled with their foals. He kissed at her chest, then moved downwards, biting gently at her flesh.
She pulled his head up and gave him a long kiss. When she pulled back, Tom noticed that her nose appeared to be smaller and turning a reddish hue, as if she had a bad cold. She suddenly stood up, wriggled free of her jogging bottoms, and leamed in close to him, whispering.
"I need you to fuck me Tom. Please I've needed it all day. Please make me yours."
Melissa threw herself onto the bed. landing on her hands and knees, and presented herself to him.
Before Tom's very eyes, Melissa arched her back and bent her legs as her arse swelled even larger. Her feet suddenly burst from her slippers, twice their normal size, as the base of her spine bulged, a small round tail solely inching itself along her enormous backside, little blonde hairs already sprouting from it.