For Arion you need to have a date with him (the one in which there are two Nymphs that talk with him), than ask Rose for advise, buy from her a tulip, give it to him, return to the stable after one day.
For Dulrig is more complicated. Try to follow my guide (link in the description of my profile) the things to do to obtain Dulrig's first Heart have DuI in the "HEART" column and if you want you can filter that column so maybe it's simpler to read. If you still don't understand I'll ry to eplain via text.