"Doahae" (도아해) is a recently coined term by a member South Korean boy group SEVENTEEN. Dokyeom (도겸) created this term as a contender to his bandmate's term, Horanghae. It is a combination of the first syllable of Dokyeom's name, "도"/"Do", and "좋아해"/"Joahae", which means "I like you" in Korean. Although it's literal meaning is "I Do you", it is usually used in the place of saying that one likes something. It has been used by Dokyeom on his various Weverse posts and moments.
a boy so precious the world doesn't deserve him. he has the voice of an angel and can dance really well, not to mention that his beauty is unique and he's also really funny, often mischievous. whoever gets to spend time with him will feel their heart warming up and wanting to break free from their ribcage, accompanied by the desire to give him the whole universe. his full name is lee donghyuck, member of korean group NCT.
person 1: i heard a voice so pure and crystalline i thought i had died and was mere footsteps away from heaven person 2: nah, you just probably heard donghyuck sing, his voice is the epitome of angelic
person 1: oh well, i still hope his voice will be the first thing i hear when i die.
Donghae is a name for the "East Sea" or "Sea of Japan." It's a body of water that essentially connects the two countries (that historically don't get along).
Hence: Donghae (when used in weeb slang) means "After a slow burn (a long waiting period) your OTP finally get together." It's meant to be used as more of a sound effect or to punctuate.
Weeb 1: IT TOOK ED 64 EPISODES TO GET WITH WINRY! FUCK! WE'RE FINALLY HERE!
Weeb 2: DONGHAE!!!