If someone is asking this question, they are quite obviously facing a massive dilemma. We are addressing someone who assumes and plans to get married but who is questioning themselves.
One possible element of the issue is trying to work out what their sexual preference or orientation really is. Some people are genuinely frightened of entering a marriage when they doubt that they are sufficiently attracted to a member of the opposite gender. They worry that they will not “have their heart in it” and thus will struggle to participate appropriately in the marriage. There is also the moral issue that burdens their mind: “Is it fair and honest to enter into a marriage with someone when I cannot say wholeheartedly that I am emotionally fit to be the person my spouse expects me to be?”
The issue is more complex, insofar as they are most likely going to feel unable to tell the person they are dating about their sexual confusion. Most probably, they recognize that discussing this with their date will risk the “whole thing going up in smoke.” This means that they are contemplating hiding this issue from the person they will marry, which goes against the basic principles of openness and honesty with a spouse. Some people may worry that they will not be able “to keep a lid on it.”
If this topic is relevant to your situation, please read the article in full.