Thanks very much for your detailed and helpful answer.
In eastern Ukraine, is there a significant differences between ethnic Russians and russified Ukrainians? How can one tell if someone is a Russian or a russified Ukrainian? How common is the inter-marriage? Is there a cultural conflict between Russians and Ukrainian-speaking ethnic Ukrainians? If so, how strong is it? And how do the russified Ukrainians react to it?
Okay, let's see. I would say that there is almost no difference between ethnic Russians and russified Ukrainians. It is more a matter of self-identification. Some Russians consider themselves Ukrainians, and some russified Ukrainians consider themselves Russians. This is where the difference arises. Its basis is that a significant proportion of people (about a half) who self-identify as Russians think that Ukraine "русская земля" (is Russian land), while people who self-identify as Ukrainians do not encroach on territorial integrity of Ukraine and recognize that they were russified.
It is almost impossible to distinguish between a russified Ukrainian or an ethnic Russian without a passport review or a detailed dialogue when he/she identifies himself/herself.
When marrying, no one cares about nationality. This is not an obstacle.
To add to this, statistics from early 2014 - post-Maidan, largely pre-war, so very relevant timing - show that 70% of Eastern Ukrainians and 58% of Russian speakers in Eastern Ukraine
wanted the country to remain united. At the same time, 73% of Eastern Ukrainians and 88% of Russian speakers in Eastern Ukraine opposed the new government's plan to scrap Russian as an official language in Ukraine, and 67% of Eastern Ukrainians thought the new government was driving the country into the wrong direction; at the same time, given the earlier mentioned statistics, most of them clearly opposed secession.
