The deuteragonist in my story,Booker, has a confused perception of love. In which he confuses lust with love, and this disturbs his love interest. Which basically tells him he's doing something wrong, but he's not sure what. He is also very assertive and does what needs to be done,sarcastic and can read between the lines. He also keeps deals, which makes an important in the story, even though it wouldn't work out in his groups' favor or even his moral compass. I have two questions about the context, Would this kill the pacing? The story is about espionage, so would going home and wondering why the main secondary female lead doesn't like him, but he doesn't know any better and therefore contemplating his life, drag the story's pacing down. Secondly, would erotica chapters be warranted? I personally don't like using it, but I want to show the intensity of it.
He sounds like an interesting character. By 'interesting,' I mean somebody you can certainly work with. As far as his thinking about his 'love interest' and wondering why she doesn't seem to like him—that should enhance, not detract, from your story. (Depending upon how you write it, of course.) Anything that gets us inside his head, makes us share his feelings or insights or lack of insight will make him a stronger, more understandable character. Obviously you need to pace this carefully if you don't want it to detract from the espionage theme, but I think you've got the bones of not only a strong character, but an excellent inner conflict as well. Just out of curiosity, are you planning for his warped perception to change over the course of the book? Will he eventually realise he does (or doesn't) 'love' this woman? Is this issue going to be one of your subplots? As for erotica chapters—by this, I assume you mean sexual scenes. (Erotica is a bit different, in that it exists ONLY to excite the reader and maybe provide fantasy. Sexual scenes illuminate character, and aren't there just to ramp up the reader's libido!) Yes of course you'll need to include them, if this issue is crucial to your story. Don't shy away from writing them. Approach them as you would any other chapter. You want to show relationship, character, maybe evoke emotion, understanding, possibly show development ...the difference between what sex is like for him BEFORE he gets clued up about love, and maybe afterwards. Let us see the changes. Be as graphic as you need to be to get your intention across to the reader. There will always be people out there who wince and cringe at sex scenes, but there are also people out there who wince and cringe at scenes of murder, death, killing, boning a chicken, washing and ironing, bathing the dog... You get my drift. Write what your story needs, and don't worry about people disliking it just because it's got sex in it. They'll either get over it or they won't.
If the romantic relationship is a significant part of the story, you probably do have to indicate the characters are romantic. That doesn't mean, however, that you have to include the full description. You can "leave them at the bedroom door," as they say, and imply what's going on. There's a book I found useful called The Joy of Writing Sex. It's about sex scenes in literary fiction, as opposed to those in romance or erotica.
Why must when he is at home does he have to wonder about his feelings. To keep pace he could have these jarring thoughts at any time, some when he least expects it. And yes to sex scenes as what is lust without the sex. The reader would never get the raw emotion from Flash backs or subtle hints.