One way I look at it is is that the suffering comes from the 'ups and downs' in life, but not from life itself. For example one day we are happy the next we are fed up without any real reason. Or we feel happy eating pizza and icecream then an hour later feel guilty and ashamed. It is this see-saw affect that traps us and controls our happiness.To be free from this 'up and down' and find a happy equilibrium is where Dharma steps in.
Buddha found that the 'downs' are caused because we crave and cling to the 'ups'. We keep pursuing mundane pleasures, such as physical pleasure: films, food, sex, entertainment etc, but due to their very nature they will not keep us happy for long. Their nature is the same as all of nature, it is impermanent (anicca) and what starts will always end. We don't want them to end, we are averse to the loss of pleasure or unpleasent (no pleasure) things.
Our ignorant nature makes us cling to the pleasure, the 'ups', and averse (aversion) to the 'downs' e.g. we don't want to go to work and suffer another boring day, we don't want to stop indulging in worldly pleasure like fast food etc. We would much rather have an "up" even at the risk of our responsibilities. This is how craving and aversion keeps us under control emotionally.
The Buddha found that there is a freedom away from their control, and that is through the realisation that there is a happiness inside each one us which is much much greater than any physical pleasure and is not subject to 'ups and downs'. It is a happiness which is not subject to impermanence (anicca) and so there will be no emotional 'ups and down'. This 'happiness' is called 'nibanna' to help people to talk about it and find it in themselves. Once found then all the mundane looses its control over us. There is no 'ups and downs' as before. However what is important to note is that we can still interact with the world, we can still eat pizza, make love and watch films, but when the experience ends we are still in control (we don't go 'down'), we can go without them or we can go with them, either way we are happy (as we know nibbana). So this is why it is not nihilism, it is still a full life.
The problem is that we can become so focused on the method and the escape from suffering that it sounds like we are also saying that living is hell and there is nothing to live for (nihilism). This is NOT true, this is a "wrong view" and is not what Dharma and the middle path is about. I too had to question nihilism and found it was not the same as Dharma (Dhamma).
Please feel free to question any of the above. Best wishes
“Both formerly & now, it is only stress that I describe, and the cessation of stress.” — SN 22:86