YA Fantasy Book-Man that can use magic and makes himself invisible but young girl can see him

[Dana]

Read this book series over 10 years ago. I think it has 3 books. It starts with a struggling maybe hurt man hiding in a barn in a small town using magic to make himself invisible. A young girl/woman comes to the milk the cow and is able to see him. She agrees to give him milk and is beaten by the owners for not bringing in enough milk, they thought she spilled or drank it. She was found at a young age by this family. The man ends up taking her with him and teaching her to use her magic abilities. They travel together for the three books and end up falling in love at the end.

[David]

Hi, Dana.

Do you remember what kind of magic abilities had the girl?

Any detail about the cover?

[Becca]

This sounds like the Pellinor series by Alison Croggon - the first book is The Naming. There isn't a Google Books preview available but there is a copy available on archive.org where you can find the scene you describe by searching for e.g. 'milk'
https://archive.org/details/naming000...