Ask her for a demonstration

"I thought it seemed like something was different about you lately," you say, cautious about how you put your next thoughts into words. Maybe she was fucking with you. She did look like a new person in a couple little cosmetic aspects, but superpowers? "I mean, you're..."

"Gorgeous," She smiles, a little sheepish. "I know. I've been, uh...making some changes. But, then--you've always thought I was gorgeous anyway, right?"

It was like she took the sentence from the ether in your head--but given the conversation, maybe it was a good guess. A new look? A haircut that you somehow didn't notice?

"Superpowers." You smile, trying to stay on your game. "Are you going to show me, or is it one of those things where I have to really really believe in it to--" Your smart-ass comment is jarred by a simple gesture from her. She held both her palms out, and you watched as she levitated off the couch from her position next to you.

You slide to the far end to get a better look at what's happening, and you can't suss out an explanation. She's just hanging in front of you--still in a comfortable, seated position--but three feet above the cushions now.

"This is probably good enough, right? Like, I figured it's better than punching through the dorm cinder blocks or throwing a car down the street."

You stand up carefully, looking at the whole room. Walls. Ceiling. Your girlfriend and the space around her. The phenomenological brick wall of seeing a human suspended in mid-air with no visible support has dumbfounded you. You approach her, barely aware of her warm, patient eyes waiting for you to accept what you're seeing.

"I--I just don't..."

"So, check it out. Satisfy yourself, hon." She lifts her t-shirt up a little to show her waistline, well-fitting jeans over the barely-showing waistband of her panties. Aside from being flawless, her tummy and waist show no signs of a harness, wires, or suspension tricks of any kind. "And here--this should seal the deal." As you're close, she swoops down and grabs you, lifting you easily from the floor and pinning you to a wall.

You're actually hanging by your shirt, which she has in both her hands. She's pressing against you enough to liberate some of your weight through the tension, and you look down in awe as you see her cleavage rubbing against your own chest.

"Oh, you like those?" She asks. "I coulda gone bigger, but I didn't want to push anything too hard without at least mentioning something to you."

You have to look like a deer in headlights to her. Your cock is reacting to this more than your cortex, though. Even as you sift through a range of cliches and stuttered thoughts about this new development, your dick is reacting in the affirmative--no questions asked.

"You can...change your body too?" You manage.

"Didn't we start on that point, silly?" She pulls away from the wall, and as gravity reclaims your weight, she wraps you up in a hug and brings you back down to the floor. "Super strength, flight, seeing through things, and...well, I'm not sure how far I can push the self-modification right now, but I know I cleared up my skin and jumped two cup sizes. Like I said--I didn't want to change too much before I brought you into this."

"And you haven't told anyone else?" You ask. She smiles at you and shakes her head.

Suddenly, you're both the luckiest guy in the world, and the most worried. She's given you a window to a side of reality you never thought possible, and she cares enough about you to share her secret...but what if you make her angry? What if you can't sat--"

"Don't. I'm not showing you this to doubt yourself. I'm showing you all this because I care about you, and I trust you." She pecks you on the cheek with a kiss, and you look back at her with a wry smile.

"And telepathy," you say. "You're reading my thoughts." She shakes her head.

"It's not quite so discrete as that," She says, giving the so-so sign. "It's more like I can tell what kind of preoccupation you're having at the moment. Not really specific words. Something I've been noticing with people lately."

"But when I thought about how gorgeous you were, you literally used the words I was thinking." Her eyes lit up and she brought you back into a hug again, squeezing a little harder than you'd like.

"Whoa! So--maybe I CAN read thoughts now!" She squealed as you coughed a little from the chest compression. "Oh! Sorry about that. Still working on keeping my excitement from showing off my strength."

"So...up to now, is there anything else I should know? I mean, about your superpowers? How often do you get them? What came first?" With the disbelief flooded out by your direct experience of all this, you now began to join in her excitement. "And...have you flown outside?"