You will need to have a look on the fate line, whether there is a companion line meeting the fate line, that age of the fate line indicates that at that age an outside person will help you to shape your career. Look at the picture.
You can see, along the fate line, 21, 28 and 35 years are indicated. You will also notice that above 21 years age, you can say at 22 years, there is a line from mount of moon meeting the fate line. Do you think that line is there without any reason? No, it has some significance. Look, what the owner of this hand says,
Well when I was in 22 I did have a very good mentor but she is a lady =).
But the age of the marriage line indicates 28 years age, so now we need to look whether there is any significant change in the fate line or life line or heart line. The theory is if they look stronger after that age, that means a good marriage, if that looks same as before, that means the marriage won't affect the life and if that looks weak, that means the marriage will bring problems. That's it. You study it for yourself.