Flip flopping is acceptable in marriage intentions or even for ones already consummated, if need be. It is called clear thinking and there is nothing wrong in honestly giving such a huge life commitment decision, involving with whom to spend the remainder of one's life, a serious rethink if you have to. To help you do this, first ask yourself what do you need out of a marriage, not necessarily what you want from a marriage; and determine if the intending spouse will help you fulfill that. If not, then run to the hills as there is no need hoping to later try fixing what was none existent in the first place. This failure to uncover is the primary reason why people are mostly miserable in their marriage; in what would otherwise be a very pleasurable experience.
It is rare and precious and like a good flawless diamond, is very difficult to find. This is the reason why self-assured people do not rush into what they will later regret by either rushing out of it or grudgingly suffer prison-like term therein, while maintaining a retinue of paramours. This rare breeds would rather wait marriage out than get entrapped in a hellish situation. But at the end of the day, it is for everyone to decide and determine what works and what does not work; and what he or she considers utmost importance - either to marry or not to marry and why. Admitted it will be good to find the three Cs in every given marriage; but life does not always work that way, which leaves you with choosing what is more important to you in order of hierarchy and then proceed accordingly.
But always remember that while a marriage can survive childlessness, financial difficulty and occasional general problems/discomforts including health issues, it cannot and can never survive incompatibility of spouses. So once you find the lucky one, your soul-mate, be thankful and grateful; and then work it to make it work for you. Always ask yourself what can you do to make the marriage work better as you pray that your partner is similarly disposed and wired too. If mutual, it turns into a bliss with each spouse seeing him or herself as the missing link and then works tirelessly hard to supply it in fulfillment of the partnership. However, if you do not find any of these three Cs persuasive enough reason for taking that great plunge, then consider flying solo.
You might be better off just remaining single and not feel needlessly yoked down just to yield to societal pressure. It is not for everyone and the good news is that it is not compulsory; so you can damn anyone who mouths off about your single-hood. Marriage is not an obligation as Jesus never married; neither did Mary Magdalene nor the pope, his cardinals, archbishops and reverend fathers. Better still, you can also simply ignore them as busy-body meddlesome interlopers, who are up to no good; and only interested in muddling your happiness. Being single is a right not a privilege, so no one can take that away from you if you don't want. If you are happily married and fulfilled, then kudos to you. But either way, curb your enthusiasm and remember that you can never have it all. Be grateful and thankful for what you have, especially if you are lucky to have a fulfilled companionship. Salute.