The story itself is not really similar. I'd say they're nothing alike, but part of the cast and production team are the same. So if you've enjoyed the quality Why R U? gave you even amid COVID-19, they'll be doing a lot better now with Middleman's Love.
They both revolve around mistery, investigation and people keeping secrets. And of course, other people trying to find the truth.
Both are Thai BL and involves being the son of a mafia leader (and taking their position) and falling in love with a bodyguard.