It could be that the labor market in some industry isn't really free. If so, that's the problem—not inflation.
Or it may be that an industry is changing, and the real value of its workers' work is falling, for example because robots or foreigners can do the same work more cheaply, or because people just don't want this industry's products as much any more. In a case like that the industry may only be able to stave off collapse by cutting workers' real wages. In a market economy it's one of the advantages of inflation that it lets companies do that without the legal and political trouble involved in cutting salary dollars.
During inflation a company can cut its labor costs, in real terms, just by not giving raises. So healthy industries offer raises in times of inflation, while troubled industries don't, and over a few years of inflation the relative wage scales of different industries adjust to new economic or technological conditions. In the long run that's a good thing. Higher wages attract more workers to the work that people most want. It's the free-market alternative to central planning, and modern history seems to show that it's a lot more efficient. Inflation is an important part of how it works.
If you're caught in a declining industry with a stagnant salary while prices are rising faster than you can re-train for a new career, though, you're in trouble, all right. Periodic moderate inflation might be good for us all in the long run, but for you right now inflation is bad.
This is the great argument against pure free-rein capitalism and in favour of social safety nets and state regulations that try to keep people from being crushed when the pitiless market changes abruptly. Preventing inflation isn't the only tool in the box for doing that, though. Periodic moderate inflation has enough good effects that it's often worth letting it happen and finding ways to help people deal with it.J.M. Keynes wrote:In the long run we are all dead.