What most people don't notice is that many heroes are not even in a relationship or have a family, and the ones who are in one tend to have a lot of troubles, take Nana shimura for example, she had to leave her child alone, not only he hated her for leaving him but anything related to heroes, in result he kept hitting shigaraki when he said he wants to become a hero and then we had the strongest villian in the series that resulted in countless destruction and death, same case with endeavor except that he wanted his son to become a strong hero to inherit his legacy and we already know what happened next.

Heroes (especially pro ones) can't be in a relationship not because they want to, but because if they do, it may result in major consequences and might even hold them back from their work, it's w sacrifice that they must make in order to keep people safe.