I can appreciate understanding of my collegues on this topic of forum as none of us have had s*x education.
A small child too gets a erction. While in sleep most youth get erections specially in the wee hours. Even many get it with a little excitement , watching a movie with explicit scene, such talk , etc etc get erection. THe best of the way without test is to find that one gets erections while in sleep.
Some individuals may be temporarily not getting it for various reasons like during or after sickness etc etc.
But If one is not getting erections at all that means he has to rush for a investigations and only after getting cured ( which 90% ) will he should marry.
Physical relationship in married life is a very important need and if u can not for ever meet is then u must avoid marrying or atleast be honest at the time of proposals. You can give annonymous advert in paper that u desire a partner but who can be happy without physical relations. But u cant deceive a lady and his family on this and keep her frustrated.
And there r some rare cases where person gets erections but is a 'gay" so he does not get erection when before a lady or gets only when he thinks or is with another male. And in such situation family does not understand his mental conditions and choice and forces him to be married and have a wife.That too is wrong. It is difficult rather very very difficult to change behaviour of such a person.
So basically no parents and samaj ( community) should force a man or women to marry if they are not very willing to get married. I have seen when parents forced for a marriage then on the day of golden night many have committed even sucide. Why ??? One of the reason can be impotency, besides being gay, or having relation with another girl.
I am not saying that u must falsely say u r impotent but if u r than find to get treated and only if noy possible at all then go for papaverine injections or Penile Implant etc.. But for these extra measuers u will have to take ur wife in to confidence and both will need to under go counselling. It will be her choice to agree to unnatural ercetins or not. Read more : https://depts.washington.edu/uroweb/diseases_and_conditions-7-Erectile_Dysfunction.php