I have known this guy a long time. He has a history of depression, he does not get treatment for it in any case. About a year ago he started seeing a friend that he met through his old work. At the beginning of the relationship he seemed happy. Its been over a year now and
he says he still is not sure about her, not that they fighting or anything, but lately he will say something and she won't listen, not that she is intentionally ignoring him, but actually does not hear him at all, leaving him feeling unimportant or something.

I am wondering if this could be a sign that she is losing interest?

Just wondered probably nothing.

Sounds like it to me... she's losing interest... she is either actually DEAF and can't hear him... or she is ignoring him. I'm going with the ignoring him explanation.

Are these thing you have observed for yourself, or relayed by him? It's really hard to say what goes on between partners, or if this is how she deals with him.

LOL, young love is just as likely to fizzle after a while whether the partners are mature and healthy, as if they have personal issues that's a turn off after a time.

Maybe the problem is him and his depression. Why does he talk to you about his relationship and not talk to her?