I had one local guy who advertised for over a year. I met him twice and he was always #1 on my list if I had free time. He started seeing someone last fall, and took his ad down, and (very politely) told me he was unavailable - at least for as long as he's with the person he's now with; or perhaps I should say 'as far as I know.' He might be seeing others (and not me) but I doubt it. We still text occasionally and he's super polite. I'm guessing I'll hear from him if they break up. Not hoping for it (or at least trying not to hope for it).
Just realized this didn't really answer the question, but I feel like it's just tangentially relevant enough that I'll leave it in here.