Marriage is an institution of a society to control sex.

Sex is the basis of marriage.

I feel that marriage should be abolished as a concept.

Instead, supercede that legal status with one that allows for broader acknowledgement of kinship. Agree before a judge that you are family, with all of the rights that entails, and it is so.

Allow non-sexual, non-romantic filial adoption to have the same recognition of kinship that marriage has now.