The infinitive form of the verb is: jorrāelagon
v. C-fin. [High Valyrian Verb Tables: Consonant-final] to hold dear, to love; to need ( < jo- + rāelagon.)
From Dothraki Wiki: https://wiki.dothraki.org/High_Valyrian_Vocabulary
Kirimvose raqiros! I am still far from reaching the middle of the course. This course, HV, and some courses as Hungarian, Turkish, and also Swahili are still difficult for me because I do not understand well the grammar, so I prefer to repeat every lesson at least 50 times during a day before to advance to the next. I will do the same with other courses that I cannot understand more than 2 or 3 phrases yet, but I need to review the lessons to can remember something. I think it is a good method to keep in mind some words, also using courses with Duolingo vocabularies on Memrise and I think it is also good to practice with Duolingo TinyCards. =)
So I decided to leave off an article as I don't believe there's been any indication that one is required in English and we haven't seen a definite or indefinite in Valyrian (yet I suppose?). It ended up being wrong with the message "You need the article 'A' here". My answer was "Father loves the girl". So my question is, what about the Valyrian sentence indicates the necessity of an article in English since the English sentence does not require an article for 'father'?
Valyrian doesn't do definiteness, so "A father loves the girl", "The father loves the girl" and "Father loves the girl" are all Kepa riñe jorrāelza and should all be accepted. The error message is because the algorithm is thinking that English grammar (not Valyrian) requires an article here. When you see things like that, report'em.
In English (and many European languages), just saying "father" is indicating a very particular father -- your own. Adding an article means you're referring to someone who is a father, but probably not your own.
I don't know if High Valyrian uses the same word for the address and the title.
You could argue that the most explicit translation of bare "Father" would be Kepa ñuha (father of-mine), but I think the ñuha can be omitted without any problems if the context makes it clear. Similar omissions appear in many of the example sentences, and I speak two pro-drop languages (Brazilian Portuguese and Japanese) where it would be natural to drop it.
Yes, it is a difference in verb conjugation.