Alright, so you're asking about that classic tightrope walk in ecchi comedy-romances. It's a whole genre balancing act, and honestly, when it fails it's just cringe, but when it works? It's pure serotonin. The core of it, from my reading pile at least, hinges on the humor defusing what could be awkward or overly lewd tension, turning it into shared, character-driven comedy instead of just fanservice for its own sake.
Take something like 'The Quintessential Quintuplets'. The ecchi moments are often slapstick—characters tripping, misunderstandings, food fights. The 'romance' is the emotional throughline of Futaro trying to connect with the sisters. The humor makes the intimate proximity or accidental groping feel like a genuine, funny mistake within the story's logic, not just a posed illustration. It keeps the tone light so the romantic feelings can develop in a sweet, sometimes clueless, adolescent way.
Where it gets tricky is in series that lean too hard into the 'harem protagonist is a pervert' trope. If the humor is just the male lead being a creep and getting punished for it with violence, it stops being romantic and starts feeling mean-spirited. The balance tips when the female characters' reactions feel like genuine personality—embarrassment, playful retaliation—rather than a standardized 'tsundere slap'. The romance thrives in the quieter moments between the comedic set pieces, where characters actually talk. The ecchi humor can't be the only form of interaction; it has to be the seasoning, not the whole meal, or you forget why you're rooting for them to get together in the first place.