But they are not expected to be sexually intimate until after the wedding. This is the Iranian solution (which is perfectly acceptable in Sunni Islam as well) which allows for dating before the wedding.
Note that this is not a loophole, this is perfectly in accordance with Islamic manners: There are all kinds of subtleties involved with this process, and Islam does not strictly prescribe the exact way it is carried out, as long as there is no intimacy before the nikah.
And, if after the nikah they want to start living together as a husband and wife (without a wedding ceremony), they can do that too, making the nikah the wedding too.
In Iran too, sometimes the nikah and the wedding are on the same day, other times they are separated by long periods of time.
It is ultimately a matter of conscience between you and God.
It is very easy for us to find excuses for our sinful desires and to say that our case is different.
They are instead strongly encouraged to get their families involved and to maintain a formal relationship until after the nikah.
For someone living in a different society, what they do could be different.
The time between knowing someone and marrying them could be years.
When two people are interested in each other, Islam does not strictly prescribe how they should behave with one another.
Depending on their culture, however, physical intimacy may be considered highly inappropriate until after the wedding, although technically it is allowed.
Why can’t young Muslims simply get into relationships without having to involve other people?