Marriage means different things to different people. For those that consider obedience to God more important than their own happiness, one activity the couple could do is to imagine what it would be like for them to be married to the person 15 years from now when/if various things outside their control have happened. No one but the Lord knows what each person will be like in 15 years. What if all of these happen: (1) sex with the person ceases to be special [how much impact would disfigurement from a car accident affect your love and commitment], (2) you grow to have different interests, (3) you have different friends, (4) cultural disconnectedness doesn't get resolved [grew up with different music, different social problem emphases, different ways of socializing (e.g., texting), etc.], (5) you need to sacrifice your time, peace, profession, and hobbies to care for the person full-time [what if you don't have the financial resources disappear and can no longer get your preferred choice for care], (6) it's hard finding things you both like to talk about, and (7) one of the partners dies: what will the survivor's life be like—can they accept that?
If all these happened to two people, what marriage could survive? Is it not practically a definition of failed marriage? Examining those ideas (and others) isn't necessarily a call to ponder gloom and doom. It is an approach to try to examine the core of why one is willing to commit to God to be with them for the rest of their lives. How strong is one's own commitment to the person and God? Does one have the faith in Jesus to know He would help in every problem area. Is one willing to do what Jesus wants? How real and deep is one's (sacrificial, friend) love for the other? Do you just like being with the person? For some people, all of the above potential difficulties can be viewed as opportunities to express one's care and love to help the other (in spite of it being psycho-emotionally draining). They're opportunities to spend more time together, to fight for something each wants together, to share (perhaps mostly small) victories together. Discussing the potential problem areas can help the couple be aware of facets of the relationship need to be dealt with aggressively. e.g., perhaps starting regularly counseling sessions as soon as (or even before getting) getting married may be called for. In light of possibilities like these, it may be more apparent that it is worth quite a lot of work to ensure you are going through the events of life as one and to be alert to diverging paths.
Given that newlyweds are not going to have the power of love that people of 20 years of successful marriage can have, one can still examine: is each person still experiencing growing love? Does it seem like love will continue to grow, as well as their connectedness? How does one feel about not being able to take a break from the person?
Regardless of how sensible this post is (or isn't) one take away can be to recognize that concrete aspects of a potential relationship can be examined when one wonders "would this really work out?"