There's a cycle here, it happens to all the players not just those who RP.
They get in the game, as newbies they make a lot of friends, with time some of them become inactive and their circle of buddies starts to dwindle. It's the way of life, nothing you can do about it. But for yourself, the trick is to find new friends and play with them instead, learn to have fun in other ways. It's true that it gets more difficult when you have higher expectations though, but not impossible.
Roleplayers suffer from this affliction the most, because once you get to meet some very good ones, and they become inactive for any reason, it's like part of the game dies. And it does! But instead of lamenting over and over and over and oooooveeerrrrrrr about it, you could lower your expectations and actually try to form other friendships, get involved in other types of roleplay, create different types of characters...
In the end, this effort will pay off, because you never know who you teach to RP and what great roleplayers they might become. Some people are good at it and have no clue until they get involved.
There's so much you CAN do instead of complain about it. I've had enough of this "defeatism" as UtM called it.
Kudos for the idea of these Roleplay lessons. Organizers - feel free to ping the GM team for help / advices, whatever. We may or may not be able to help with all requests, but we can surely try.
