Regular breaks are important to doing anything. Doing anything for too long, without rest will cause more than just dissatisfaction with the game, it actually will cause you to think that what you're doing is repetitive, hence releasing less dopamine when you do something that is really awesome (or at least you think it is) in the game.
Dopamine is a hormone which makes you feel happy for doing things.
This results in what's happening to you right now, a "down stage" making you feel bored of the game, and feeling like it's boring, unlike what you thought when you first started playing the game. Taking a break and coming back later will allow your brain to have calmed down, especially if you feel like you're not improving, and will make you have considerably more fun. This break can last from 30 minutes to even indefinite periods of time. It may be that you actually don't like the game very much and were just hyped on it when you first started playing.
Take a break! Play other games. There's a plethora of free games online that are available for you to try. Since you're in Europe, I can't recommend Mabinogi, but Cabal Online might still be active in Europe.
Alternatively, you can find a song that you REALLY like and play that, or songs like that. A song that you like is more likely to keep you attached to the game instead of turning you off, but it's important to remember that breaks are also a key part of playing the game, so don't just play that one song over and over again, as the same "down stage" will occur, and you will stop liking that song, and you will also stop liking the game, as it will feel repetitive again, and there comes a stage where you just can't beat your old score on a song, making you feel like you're not improving. Once again, that reduces dopamine releases. So play some other songs, or make some of your own! Variety is the spice of life
Friends are also a good alternative to being bored. This one explains itself. So if you have some friends with free time, get them to play too!