As literally as I can make it, "You are a super nice-guy, that no medicine can cure"
In the context of the uncyclopedia article, it is "nice-guy syndrome", much related to the phenomenon Westerners may know as the "friend zone".
i.e. When a girl says "[I'm sorry, ] you are a nice guy, but..." - Let's just be friends - I don't want to lose this friendship that we have - I have always seen you as a big brother - I don't think a relationship between us is right - My family doesn't approve of you - There is someone else I like - I'm sure you'll meet someone better than me - Work is busy, it's not a good time now - I live too far away - Our horoscopes are incompatible - etc. etc.
And "thanks for chauffeuring me, thanks for coming over to fix my computer, I'm going out for a moment to have a "hot dog", why don't I introduce you to my boyfriend sometime..."
I know it's not quite that situation between Adol and Terra, but I just thought that line taken out of context is funny.