Marriage is considered the most special and dedicated decision that one takes in his life as he/she is ready to bone in all sense i.e. physical, mental, and financial. The two become one to form a new family of their own where they may face ups and downs, raise a family, be together forever in all the situations of life.
As others have already mentioned, there is no ideal or right age for marriage as many are ready to start a family when they are 21, some at 25 while some wait for till they feel they are ready to start. The same rules imply to girls and their family but due to biological issues, they tend to marry their daughters at a young age.
When we talk about getting a perfect mate, can't we think in the other way that as the boy waited for the correct time, maybe his soulmate may be waiting for the correct time too. Many have their own way of thinking, their dreams, ambition, problems(financial, job, family), home, etc and would like to complete that before he/she can dedicate their life to start a new family. It is also good and point to note that if everything falls in the right path, one can plan to have their marriage early and take time to spend more time with each other before they move forward and grow their family with a new member.
“The most important thing in life is to learn how to give out love, and to let it come in." — Morrie Schwartz