You’re not getting it...
Marriage is a federal issue because the states are obliged to recognize each others’ marriages. The alternative is that you would have to resubmit for a marriage license every time you crossed state lines... and then you’d have multiple marriage licenses, creating all sorts of legal contests over jurisdiction in the event of separation.
I'm sorry if the Constitution is not as convenient as you would like, but it is worth it. You, me and everyone here are slowly trading freedom for convenience and one day we will all be slaves because of it.