Now that we're done with generalizations and stereotypes, let's take a more scientific stance. A shift from subjective towards objective or at least to the kind of subjective that's generalized, so it becomes more or less objective.
It's well known that our environment shapes who we are. In the same way, Russian girls' character is also shaped by their environment. The environment they have to live in is not the most friendly one: it's often aggressive, it wants to use them, it's full of lies and drama. So they develop some sort of hardness in order to protect themselves. This hardness in character, in turn, produces even more aggressive behavior towards them, creating a self-reinforcing feedback loop or a vicious cycle, which is very hard to escape.
In order to break free, we need to understand the current situation better, so let's turn to statistics.
Google has a very good tool called "Keyword Planner" to help advertisers bid on the most popular search terms. It shows how many people search for a given search phrase and in which context.
What we find out is that on average people search for the "Russian girls" about 1 Mln times a month, peaking in March (spring time, perhaps). We also see that most of the searches occur in the context of "dating" and "sexy". So definitely there's interest either to date them or to have sex with them, or both.
Compare this with the Google results for "American girls" or for "French girls":
Both are not nearly as popular (French girls surprisingly do very badly on Google's most wanted list). Most people are interested in American girls in the context of finding a new girl's name, dressing them up, or getting a doll. While French girls are traditionally associated with being pretty and the French kiss, which is understandable.
This very superficial and yet quite informative study of the Google search terms reveals the fact that Russian girls are insanely more popular than their European and American counterparts and that they attract a level of interest that is very much related to some sort of proximity, even intimacy we might say.
In other words, Russian girls, more often than girls from other countries, are looked at as objects of sexual desire. In a conservative and authoritarian country like Russia this sort of demand produces is a very categorical attitude towards sex: it's either too superficial or too precious – with nothing in between (rare exceptions exist, of course). Faced with this choice, men tend to make their intentions seem more precious than they really are (who wants to seem superficial?), which, in turn, crystallizes this sort of attitude even more. Other men act like assholes and that doesn't help the situation either. Relationships turn into games of commitment and power, sexual attraction turns into currency, and that's when you start understanding why everyone is so crazy in Dostoevsky's and Tolstoy's novels.
The only way out, it seems, is for the both parties to take it easy and chill. Inclination towards extremes is an important part of the Russian character, but intersubjective relations is the one area where it gets pretty nasty exactly for that reason.