it depends on the people, circumstances and maturity levels..
my first love was a brother in the congregation I grew up in... ironically after we each married people and my first child was born, he told me that he (my firstborn) should have been ours..
but it was not to be..
and we were both too young.. it could never have worked..
But I know people who have found their love first and are still together, so for some.. sure it can work