During the very early days of their being together:
The Alpha had noticed it. And now that he had, the question wouldn't leave him alone. And also, how on earth hadn't he noticed it before?!
...Still, he needed to either let this go or ask her. He wasn't the type to let such things lie any more than she was.
So...
The Alpha: My Lady, may I ask a presumptuous question?
The Dark Lady: ...OK.
The Alpha: That diamond ring on your finger...
The Dark Lady: ...Oh. Are you asking if I'm already attached?
The Alpha: No. I'm sure you would have told me if that was the case. But... even if it was in the past, emotions don't always follow logic, so...
The Dark Lady (raising her hand so that the band and stones caught the light): Nice, isn't it? I bought this for myself.