I don't personally go in for or support the institution of marriage or even the idea of the nuclear family which I believe simply upholds patriarchy under capitalism. Making complex legal arrangements prior to marriage would be difficult because circumstances change, antagonisms arise and people develop different needs and aspirations over time.
It has always been the case that men have sought to impose control over women's reproductive capacity and they have created the means through marriage and dna tests to ensure their progeny is theirs alone. Is a father someone who sows the seeds or the one who brings in the harvest? If a man, any man has played an important part in parenting a child, over a long period of time where that child has a bond with that person, it is right that the courts take this into consideration. From everything I have read and know of the family courts, men are in the main gaining ground and being able to impose their demands quite well enough. But do I support the rights of violent men or men too silly to take charge of their own contraception to make demands? If men are to have full equal rights, it might include forcing a women to continue with a pregnancy she doesn't want outside of a relationship with that man.