Ashrama vyavastha or system of stages of life as per sanatan vedic dharm has 4 ashramas or stages of 25 years each. 1. Brahmacharya (student)
2. Grihastha (householder)
3. Vanaprastha (forest dweller)
4. Sannyasa (renunciate)
Clearly marriages are not advised before 25 years.
Brahmacharya Ashram is the first stage of life.
It is marked compete when one has completed education and acquired wisdom (adulting).
Let's call it attainment of stable career & profession.
Grahsat is 2nd stage which begins AFTER successful completion of Brahmcharya.
Grahast is when you pursue romantic life & your 'desire' of progeny. We call it married life.
3rd ashram is Vanprasta, which starts after completion of grahast.
Completion of grahast is the point where you have enabled sucsseful completion of brahmcharya for your offspring.