Obviously the easiest way to do this is to become a writer. Otherwise, the specific problem here is that sometimes you just don’t want to write a sex scene. You’re either writing an all-ages strip, the sex scene would disrupt the flow of the story, or it just feels wrong for the situation at hand. In those situations, it pays to know a few ways to deal with the need for an intimate scene but without the sex.
Dancing: It happens in the movies all the time: Instead of having the characters go hot and heavy, they engage in a scene of slow dancing, usually all by themselves. It ‘s a nice intimate moment between a couple, with all of the focus on the couple. It allows the artist to draw a nice, close picture of them, heads upon shoulders, nice and tight, sharing an embrace without it being on the sly, so they can lose themselves in one another. Sounds sort of romantic, right? This is probably the best solution.
The Slow Kiss in the Rain: Done right, this works really well. The rain allows a nice silhouette on the couple, allowing the artist to focus on the couple’s emotion. If the couple is having a long day, the slow kiss acts as a nice break from all of the action, allowing them a few seconds to lose themselves in the kiss. It allows you to slow things up for a moment, while at the same giving your characters a second wind. It doesn’t require rain by the way; anything that screens them works, even a quick blur.
The Fast Kiss/Slow Reaction Shot: One of the couple gives the other a quick smooch, and rushes off even as the other reacts to the kiss. This allows the action to keep up while giving the couple a necessary romantic moment. It only takes a few frames to accomplish, but does so much to show the relationship of the characters.
The Surprise Gift: Although one of the characters is doing something else, the other character finds or uncovers or even has delivered to him or her a small present. The target character smiles and then finds a place or use for the item in question, usually remarking how perfect the item is. It’s a fun little scene, and moves along the relationship. This also allows you to move the plot along through a small coincidence (you know that aggravating situation when something happens and it comes off as if by luck, like when the bad guy just happens to run out of ammunition or someone shows up at just the right time?), but one the audience should forgive you for.
The Boring Meal: Sometimes you just need to slow things up a bit and give the couple some time together. This is when they should eat together; an intimate dinner with them in each other’s arms, possibly feeding each other. The annoying comedy version has them at the ends of a long table, but that should be avoided unless you can actually play it for laughs. Otherwise, the couple should disappear and just enjoy some time together under the guise of doing something practical. Although this adds an intimate moment to the relationship, it needs to be boring; the meal needs to bring them closer and having any action will have the opposite effect.
There are obviously other ways to go without sex, but these should get you out of most situations. Just remember that you need to emphasize their relationship, and sometimes it just takes slowing things down a bit to accomplish that.