At the beginning of August, there is LTC halving. Does Btc and ltc move together or does ltc increase independently?
I still do not feel any frenzy about the Litecoin halving and its looking a bit dissimilar to what it was the past time. Or maybe it's too early to judge. Secondly, both btc and ltc are quite independent despite the fact that ltc traces back to btc but then it's still an altcoin
Too early to judge, in my opinion. Although past performance does nor equate to a success in the future, but judging from its past halving, LTC did quite good, to be honest. Other's have said that LTC is going to die, guinea pig for its big brother BTC, but so far it is holding on its own. So personally, I think something big will happen after the halving and it might go near or even top its previous all-time-high.
Hard to say whether the market will be boomed away after the halving but like what you've said there's always chances there's supporters who wanted to take the advantage and take the risk of investing, there's an open opportunities you need to make your move and take the step bringing good value to your invested money.