Ah, the benevolent Count de Villeforte. He's pretty free with the romantic advice to Emily, though he might have some marital problems of his own shoved under the rug. He even suspects that he might be crossing the line, kind of:
"Many young ladies, circumstanced as you are, would think my conduct, on this occasion, and on so short an acquaintance, impertinent […]" (3.23.64)
But then he goes ahead and tells Em that she shouldn't be messing with Valancourt, establishing his place as the Dr. Phil of the book.
Let's be honest here. The Count de Villeforte has his own dog in this race (if marrying Emily can be called a race). He wants his buddy Du Pont to end up with Em, so he pulls some strings to try to make that happen. It's a Father-Knows-Best type of deal.
How does the Count get away with being Em's de facto adviser? He knows she misses her dad on some level, so he steps in as that father-figure in her life. Of course, he's got a daughter right around her age, so he knows some of the typical teenaged drama that characterizes a day in the life of Miss Emily. But, hey, he's also a pretty decent guy. When Valancourt's name is cleared, he grudgingly "dissipated every doubt, as to the past and future conduct of him […]" (4.18.29).