The is JMO and not Halacha La’Maalaseh but its not so far off what Rav Yosef and Rabbi Horowitz said
In the more charedi world people tend to marry people of similar backround ie Belzer Chasidim marry other Belzer Chassidim (or someone from a group related to Belzer) or yeshivish marry other yeshivish, you wont see many Belzer chasidim marrying Yeshivish people (not saying it doesnt happen, its just rare)
However in the more modern communities people will marry people from other groups. An Ashkanez will marry a Sephard or a Litvak will marry a Yekke and the lines between these groups are being erased as ties to the Alter Heim is being forgotten and erased. I mean really how many people really consider themselves Galizianers anymore.
When people from differnet backrounds marry, you sort of have to compromise top make it work, especially since nowadays people will spend more time with the in-laws than they did in previous genarations. In previous genrations many times the woman left the town where she was from to move to the husbands town and rarely saw her parents again, today spending Shabbos and Yom tov with the womans parents is normal