It's been a while so I am not sure how *good* they are, but these poly couples in GLs were at least enjoyable enough for me ngl; at the very least, the relationships felt like actual relationships, rather than some fetishised slop:
Goukaku no Tame no! Yasashii Sankaku Kankei Nyuumon
There's Weird Voices Coming from the Room Next Door!
Lumino...... reply
