“Before”, one would choose (or even be strongly recommended) a partner, commit, and make it work.
Now (culturally), one expects to find the absolutely perfect person/flavor and have everything worked out at the time of selection.
You can see how such an attitude would drastically limit the choices.
Another difference is that nowadays partnership is expected to include that person being the perfect lover, perfect co-parent, best friend, partner in crime, sometimes therapist etc. while in the past the expectation that the romantic partner would also be someone to entertain us or always understand us or share hobbies etc. was much much lower.
obviously not absolutes but more of a cultural slider which limits choices and puts more stress on relationships.