Maybe not in recent times, although a number of European countries have had their share of internal political strife. I don't think anyone is immune to it. One difference I've noticed in Europe is that there seems to be more parties represented in their governments than we see the two-party lock-hold on power held by the Democrats and Republicans in the U.S.
Taking a quick glance at your own parliament in Italy, it appears that multiple parties have seats:
Italian Parliament - Wikipedia
9 parties represented in Italy's parliament, as opposed to the U.S. Congress:
There are three "independents" in the Senate, although they're mainly with the Democrats on most issues.
Then, we wonder why we can't find any "middle ground" or build any kind of bipartisan consensus on most issues.
Oh, there's been plenty of politically mixed marriages in the U.S., with Democrats marrying Republicans quite often. My father was a Republican and my mother was a Democrat. They divorced when I was 6. A lot of people might have friends and family members who are in the opposite party. In my experience, I've found that some people can still disagree on politics yet still maintain a warm friendship and loving relationship with friends and family. However, there are others who are unable to disagree amicably and end up becoming lifelong enemies.