Warning: Spoilers for Miracle Day episode 7 and 8.
Author's Note: Personally, I believe that Jack has loved and will love many more people than Ianto. But I also believe that a) Angelo was less of a "love" thing and more of Jack's desire to have a companion, a loyal someone he could trust like the Doctor had and b) that Ianto was different from Jack's other lovers, and that he was unique and special in a way Jack knows he won't ever have again.
Summary: Jack talks to a comatose Angelo and realizes how important and unique Ianto was and how much he misses him, and remembers how everyone will always leave him.
Dive Your Hand In, Feel The Longing