Alternate coins always fall while Bitcoin is going down. I think that in these moments we must be very patient. Indeed, after a fall, growth begins.
Bitcoin has always been the strongest factor affecting the market, this is because almost all altcoins are traded with bitcoin, when bitcoin vs fiat drops it automatically the altcoins value also drops.
It is only on rare occasions that we see altcoins grow against bitcoin. Which is when there is an important update. The dominance of bitcoin on the entire market is still feasible and that has also shown it's effect on the present trend.