I've been trying to get Dulrig's love point, it says "fulfill all his needs" on the Munbury mountains trip but "don't be TOO eager." I got a bunch of like points by observing and slipped 5 emerines into his bag on two trips now but no love :(
It seems that you need to get his discount before the Munbury trip. You also need to let him tease the mc on your way to mountains. During his excavation, you shall protect him but not eat him out more than twice. Then slip 5 emerines into his bag. And above all, you cann't be a top.
You will need to provide him with 5 glafire stones first. Then you can find topic "discount" in Dulrig's talking list. You will gain his discount after doing some naughty things with him.