I'm playing the free version of the game and I can get past 6.9 with Nel
Do I have to release any characters first?
I focused on her a lot
At the moment, it is impossible to focus on one character. I wouldn't mind ignoring characters I'm not interested in either.
To advance further, you need to complete story quests, increase your skill level, and improve your relationships with key characters (it is enough to complete their quests, and also take some of them with you in battles with monsters).
The list of key characters is available through the "Quests" button; it indicates how many quests have already been completed.
The following will help you figure out what to do next: icons on the world map, the bartender (his rumors), a fortune teller (usually she helps with character quests).