Wow, this question hits right in my sweet spot. Intense romance and erotica can be such a tricky balance—too much plot and the spice feels tacked on, too little and it's just a series of scenes. For that intense, all-consuming feeling, I keep going back to authors who write about obsession and dangerous attraction.
'Sicko' by Amo Jones is a good example. It's not for the faint of heart; the romance is dark, possessive, and morally questionable, but the emotional intensity between the leads is off the charts. You feel the desperation and the wrongness of it all, which somehow makes the connection hotter.
Another one is 'King of Wrath' by Ana Huang. It leans more into the billionaire/arranged marriage trope, but the tension is so thick you could cut it with a knife. The slow-burn to explosive payoff is masterfully done. It's less about pure taboo and more about two powerful people trying to resist an undeniable pull, which creates its own kind of heat.
For something a bit more niche, try searching for Omegaverse stories by authors like L.V. Lane. The biological imperatives add a layer of feral intensity that regular contemporary sometimes lacks. The best ones make you forget the world-building and just get lost in the primal need.