There are lots of firsts in Paradise Lost, of course, and here in Book IV the first man and the first woman make Satan the first person ever to be repulsed by the sight of others making out. You might argue that this can't be called PDA because back then, with only two humans, the concept of P didn't yet exist; however, Adam and Eve know perfectly well that angels, of which there are lots and lots, are zipping around everywhere and are wont to drop in on them at any time. No wonder our First Parents' first act after eating of the tree was to put some damn clothes on -- ADAM THE ANGELS HAVE BEEN WATCHING US DO IT THIS WHOLE TIME. Not that their lack of shame excuses Satan in this instance, because he's straight-up spying on them and really has no one to blame but himself if he catches them in the marital embrace.
That said, I do sympathize with Satan here, because pain of longing pines me too, especially when I see others going at it in public, acting as if they were the only two people on earth when in fact there are eight billion of us now so could you take that somewhere else, please?
And yes, Satan does have a girlfriend, because another thing there's lots of in Paradise Lost is incest. Which kind of brings up some interesting theological questions because God arranged it so there'd have to be incest. Adam and Eve are so closely related that they used to be a single person. Yet somehow their being married is totally cool, but when Satan bangs his daughter it's a problem? I mean yes, it is a problem, because incest is bad and gross, but this daughter was created in just the same way Eve was, out of a (cisgendered) male body. (Which is totally not the way reproduction works, guys, and I assume the Adam's-rib thing got written into the Bible because of male anxiety over the fact that the power to make new humans -- arguably the most godlike power a person can have -- rests primarily with women. Maybe John Milton had twice as much castration anxiety as the guys who wrote Genesis and so had to tell that story again.) See, back before he fell and was just plotting to overthrow God, one day Satan got a really bad headache and suddenly a fully grown woman popped out of his head, as sometimes happens, right? Satan was freaked out at first, but because she'd been born via parthenogenesis, this woman looked a lot like him, and because of that he took a liking to her. Long story short that was his daughter, Sin, and they had a lot of sex, and then he forgot all about her until after the war in Heaven when she appeared again only this time she had a tail instead of legs and Satan found out that not only did he have a son who was also his grandson but in addition he had a whole bunch of grandchildren who were also his great-grandchildren and were also, for some reason, dogs. (This is another first: Satan and Sin are the first people to reproduce in what is now the usual way for humanoids, by copulating. Maybe Satan was surprised to meet his suddenly rather large family because he hadn't known that pregnancy was a thing. When did God invent that?) Satan is a bit put off by all this, but Sin hails him lovingly, describing herself as "thy daughter and thy darling." And that's super gross, naturally, but then how come Adam gets to do it with the woman who popped out of his body? I call bullshit on that.
But back to firsts. I'm sorry to say that Adam is not only the first man but also the first mansplainer, because Eve's lady-brain just doesn't understand things. See, it wasn't formed to:
Not equal, as thir sex not equal seemd;
For contemplation hee and valour formd,
For softness shee and sweet attractive Grace,
Hee for God only, shee for God in him.
Well, that's tiresome, but not unexpected -- it's Pauline teaching, after all -- but my question is, what is there to be valorous about in the Garden of Eden? If God made men to be brave and women to be submissive, that's just a free ride for men as long as they don't eat of the tree, right? Because Eve still has to be submissive to Adam, but Adam doesn't have to do any work to protect her from anything or provide her with anything. He gets to just sit around and mansplain -- that's the "contemplation" part -- and boy does he! That's why I like Satan way better. Satan asks others for their opinions and listens when they talk. Like his BFF Beelzebub there, whom he addresses in Book V like a tween at a sleepover:
Sleepst thou, Companion dear, what sleep can close
...Thou to me thy thoughts
Wast wont, I mine to thee was wont to impart;
Both waking we were one; how then can now
Thy sleep dissent?
Get a room, you two!