Idealistically, 50/50 would be perfect, but life isn't perfect.
There is a reason why in every culture there is a saying that a woman should marry a man, that loves her a little bit more than she loves him.
Men as a whole generally are not as compassionate as women. Women tend to do more in relationships, even if the man loves them more, as they are nurturing and giving.
Many of the guys will say the opposite on this thread, but deep down the one that they will treat better, and be happier with is the one he loves more than she loves him.
Ladies, if you are getting to know a guy and you realise that you like him more, and are more attached, leave him alone. Throw the whole man away.
Step aside so he can marry the real love of his life, as it's clearly not you.