Countries have a limited amount of resources at their disposal, and for the most part keeping these resources for people that have been living in said nation for their entire lives tends to be a higher priority than letting large numbers of immigrants and refugees in at this current point in time. However, there are a few loopholes that can be taken advantage of, and the main reason why these loopholes were put in place to begin with is so that people would have at least some kind of recourse that can enable them to live better lives in a highly developed nation.
The concept of marriage based citizenship might sound a bit dodgy to you, and you might find yourself wondering whether or not it is a truly legal act. The thing is that law support for marriage based visa has been quite widespread recently, and as long as you get married in some type of ceremony that can benefit you and is recognized by the legal authority of the country that you are planning to move to, there is no reason why anyone would doubt the legitimacy of what you have taken part in.
Most countries have some kind of marriage based citizenship policy, and in order to take advantage of these policies you need a lawyer who is fully aware of the ins and outs of the political system. This lawyer should ideally be able to grasp the kinds of factors that are in play here so that they can give you sound advice which you yourself can end up acting on. The due process for this citizenship has been spelled out on various websites which you should check out.