Sitting in is not a Chassidish minhag, it is a frum minhag. There are some very real Litvish yeshiva boys that are sitting in these days and making a decision after 4 times. So far there have been no divorces among this group but from those of you who are busy looking at the gashmius, there are divorces, broken engagements and committments to such as shmutzbook(facebook). Rabbi Ephraim Waxman wrote an article about dating in a Jewish Observer a few years ago. Try to get an issue and then you’ll see the truth. Going in public places as the weather gets warmer is like walking in a zoo of humans. Statistics of divorces among frum Yidden who are Chassidish, although unfortunately more heard of than years ago is still far less than among other types!
By the way there are people with beautiful homes who offer there homes for sit ins, so that the atmosphere is more relaxed than in ones own home or that of the other side of the date.
Yes, i am speaking from experience of having married off all our children B”H without these narishkeiten, but focusing on what is important in marriage and how the children will grow together.