Out of order?

There's quite a bit of background to this stroy but I'll give you the basics: basically there's a kid at college (say, 'D') who apparently knows me and says alright etc, tho I'm still yet to know who he actually is. Anyway, he was trying it on with my girlfriend (sending out of line texts, coming to see her at work all the time) regardless of the fact he's got a 9 month relationship of his own, and knew we were an item.

Me and my missus had a little break a while back from each other, and then a couple weeks ago we came clean with each other, like telling her I kissed a girl at a party, and she mentioned she'd met up with this kid and kissed him but nothing more, although he did try. Which is fair enough, she's not actually done anything wrong, and I trust her when she says that, though I think you'll agree it's a bit bang out of order on this kid's girlfriend him trying it on with other people.

Anyway, the part that really baffles me is when I got back to college the other day, my mate Dave came up to me all like 'oh, why'd you say you were going to beat D up?', which was the first I'd hear about it especially considering I hadn't mentioned the situation to anyone at college. Turns out D was telling people that I'd been threatening to beat him up, and dropping it into conversation with random people. I've heard from other people as well that he's been talking about my girlfriend, and ultimately me quite a lot as well. Why?

As well as this, I was talking to my close mate about the whole thing as he knows D's best mate and asking him if he could shed some light as to why the fixation on us, and coincidentally we bumped into D's best mate. My mate asked him if D was about, and D's mate offered to give my mate D's number but declined. Next thing I know, I'm getting a phone call from my girlfriend ranting and raving at me all like "why the fuck are trying to get hold of D's number, why are you trying to check up on me?!". She later told me she'd spoken to D and D's mate on the phone, who'd obviously twisted the story to make it sould like I'd been asking for the number and then proceeded to tell it like that to my missus. This again confused me as to why they would do such a thing. The only thing I could conclude was jealousy, or just an act of bitterness for D attempting to get with her, but her coming back to me at the end of the day? I really don't know..

Sorry for the lengthy-ness of this, but wondered if anyone could shed some light. This is really doing my head in, seems like I've got to totally avoid some situations in case they get back to my girlfriend all twisted and distorted making out like I'm a cunt, all in the wrong. Why should I have to? And why all the apparent attention put on us?! Fuck sake some people needs lives..