Let me begin by saying that the act of sexual intercourse in a role-play is next to useless in terms of fulfillment and/or enjoyment. It's nothing, it's words, and it's especially weird if a male GM is telling another male player about what the male/female partner is doing to them.
In a sense, the fact that the act is transparent to the player can diminish the characters sex drive. It depends on the personality and bearing of the character. If he is a lady-killer, perhaps with a high attractiveness or seduction, he may pursue women but for what? A squeamish GM might just say; 'You start kissing and then go to your room. Heh heh.' End of story. Many players simply give it up as a lost cause.
Is it important in role-play? It is if you want realism. Humans were meant to procreate. It's in our genetics. But that's real life. Some players just can't see the point. They're in it for the action, the money, perhaps the thrills of driving a sportscar not invented yet.
In my early days it was just an inane and stupid thrill. For young geeks who sit in dark rooms around tables with dice, even the thought that they have got lucky is a trip.
Maturity and a better understanding of the other sex have changed those ways, however. Now, attraction between the sexes, flirting, relationships and the act itself have a raised importance. Role-play. Pure and simple.
Note: This essay speaks from a very male point of view. It's not denying that plenty of females play. I'd love to see more. The president of my Uni RPG club was a 'chick' and she was a hot role-player. But I would say the fairer sex make up only about ten percent of the role-play community, at least here in Australia and from what I've seen.
Personal relationships help shape a character. How they relate to friends and lovers. Are they shy, brash, formal, sleazy? Does their demeanor change when facing a prospective 'girlfriend' or partner? The toughest solo may stammer and blush when propositioned. A normally quiet tech might just have 'the touch', that affable charm that sends women flocking. It's another facet for a well-rounded character.
Sex and love in C-Punk is about hooks and turns. If you've had experience with a rough relationship, then you can apply it to the game; you know how it goes; how that goddamn bitch just wants her own frackin' way all the time and just nags nags nags GOD I CAN'T STAND THIS!!; sorry, getting ahead of myself.
Casual sex can be dangerous; especially with AIDS-II and Lepro-V, or whatever horrid diseases are floating around in your game. Does the character have contraception? Bull-headed players may still think it's up to the girl. It's alarming how many good-looking NPC females have a contraceptive implant; even scattered throughout the C-Punk books.
This leads to interesting stuff. Applied to Cybergeneration also, where teen pregnancy can really wreck your week. The character may have to help raise cash for a termination or take a deep breath and go ahead with it. Or grab his board and leave town.... It forces the character to make ethical decisions that moreover help to shape them further.
The old 'seduction roll in a crowded club and a quick fuck later' is dead. It achieves nothing. Sure it might happen once in a while, but sex and love is important for other reasons. A character might be playing the field and vying against another for a girl's attention. Of course, in the world of C-Punk the rival can be taken care of with a 12mm slug in an alley, but you don't know if he was meant to pick her up for a hot date at the Budokkan that night.
Once in a blue moon a 'punker might have the perfect relationship. But this makes for dull role-play. Their partner could be flighty, demanding, obsessive, carefree and promiscuous, picky or prone to arguments. Don't pick one trait, try a few. It's more lifelike.
A character could be two-timing, which leads to plenty of delicious situations and often the rest of the players sit around pointing and jeering as the player squirms under the stern admonishing of the GM playing an irate partner. I recall one game where a character was in conversation with his NPC girlfriend and called her by the name of another girl they were protecting and he had gotten involved with. He instantly took it back but the fact was it had been said and his girl had heard it. He slowly shrank in his seat as a very one-sided shouting match began.
Women with dark secrets, bored wives looking for the edge (or edgerunners), scared nymphettes looking for protection from an ex, this is what it's all about. The fact they have to contend with this and still turn up to plan the next extraction or black op can really harass a player. Bags under the eyes can clue the other characters in.
The act itself. How to approach it? It depends on the level of decency you'd like to set in your game. If your players are a pack of lewd bastards who want every sordid detail, and you're capable of providing it, why not? You might be more of a 'Purple Rose of Cairo' GM, fading to black just as the player gets a better grip in a locked embrace 'Where's the fadeout? There's always a fadeout when we kiss'.
I tend to concentrate more on the sexual tension and romance than the horizontal polka (or wall-bang if you're so inclined). The way she licks her lips, leans forward when you're talking, if she stares into your eyes or glassily at the wall when you tell her about your new gun. If you're at a bar, are others scoping her out? Is she scoping others? A woman in a well-cut suit with a hint of black satin at the breast is also sometimes better than describing her as 'oh, pretty much half-naked with some stuff sprayed on'.
Atmosphere. What music is playing and what's the lighting like? Is the corp exec you're discussing hiring fees with ordering another bottle of champagne? (Is she coming on to me?) Body language described to players is great. If she links arms, or holds hands, or flings herself bodily at you in an expression of affection. The way her hips move, whether she looks over her shoulder back at you. Make the players want to get involved.
Never play them as tools, cardboard cutouts or nymphomaniacs with nothing better to do. Don't try to understand the mysteries and vagaries of women, just try to emulate it. Play them as individuals with wants, needs, desires. And guess what? They don't want to have sex all the time! (This may be obvious to some but I'd like to cover all bases).
It's sometimes hard to maintain the illusion that a svelte blonde vixen in a fire-engine red shift is propositioning the character when you're a very masculine fellow, deep voice, hairy forearms and all (I can only wish). Adapt and modify. Find your own way around it. Conducting the conversation in third person- 'She says, I want you so bad I'm gonna pop' can help, but if your players have reached that plateau where suspension of disbelief kicks in, and the GM can be anyone, then great!
Have fun getting your players into all sorts of uncomfortable and perhaps even squishy positions. You can take that last sentence any which way you want to.
Kris