imminent netorare
As netorare involves infidelity in which someone close to the protagonist (usually someone's lover, though the dilution of the word has meant that it has also been applied to friends, unrequited love interests, or even relatives) is usually unwillingly seduced and stolen away, imminent netorare involves images where that taking away will soon occur.
Posts on Danbooru tagged with this should include doujin covers for doujin where the theme is netorare; pools and parent posts where the end result is netorare; and the moments before netorare occurs. The one taking the loved one can be present, but cannot be actively penetrating or otherwise taking the loved one.