Intensity is such a mandatory element in romance. Especially in Erotic romance. That soul-gripping need between the characters is what really brings the reader along for the ride. I personally have to FEEL everything. I have to want that character to touch, or be touched. Kiss, or be kissed. Fucked, or be fucked.
As a writer, it's a fine balance. You want the tension to jump off the page, but you have to be careful not to push it to a point where it seems... off. That's definitely where showing and not telling comes in to play. I have a hard time with writing sex scenes. It's not that I don't like writing them--I just always have this anxiety about them. I want them to be sexy, graphic without being squicky, and definitely intense.
My characters help with these scenes. The more intense the character, the hotter the scene.
One of my current WIPS is actually a rewrite of a former story I wrote and published online about five years ago. I'm taking very little from the original, only minor plot elements, but the most important part that is staying in the story is my Hero.
Tex, as he has been reborn, is as intense as they get. He's consumed by Eden. Every part of him loves her. He craves her, has held on to memories of her and the way she made him fall in love with her for years. When they reconnect, the fireworks they'd ignited in their youth become full-out bombs. That kind of intensity is a blast to write. When his every thought, every action belongs to his girl, you know that once he gets to share that adoration with her, it's going to go off.
Tex takes intense to a whole different level. He will come off as obsessed, controlling... basically dyed in the wool Alpha barbarian, but at the heart of his behavior is love. He cares. Admires. Worships. Worries. Protects. Possesses. Loves. Everything about his character is full color. Red, red, red. He doesn't do wishy-washy. He's very driven, very determined and very ambitious. This carries on to every aspect of his life, but when it comes to Eden, he goes 110%.
Whenever I write a character like this, I almost welcome the "Caveman" comments. You're damn right he is. He's completely driven by testosterone, ego, pride and his heart. Personally, that's the kind of hero I like to read. The more they beat on their chest, the squishier my heart gets. Drag me to the bedroom by my hair. Catch me if you can. Show me. All I can say to the gals that tsk-tsk the knuckle-draggers... they obviously haven't been thrown over the right man's back and been carried off to be devoured. Sorry about that, ladies. You're missing out.