The friend who notices a new interest has left room for you to change.

Most people hold a fixed picture of you and quietly correct anything that does not match it. A friend who notices a new interest is doing the opposite, updating rather than defending the version they already had. That takes a kind of attention with nothing to do with flattery. It means their idea of you is still open at the edges, which is rarer than affection and harder to give.

Think of someone whose life you have not updated in a while and ask what they are into now, with no joke attached. Then let the answer sit rather than measuring it against who they used to be.