It has also shrunk in all domestic endeavors. We have gotten used to getting what we want as fast as we want it and conversely have lost patience with anything that inhibits quick self-gratification. It takes time and patience to build a lasting relationship. Romantic love, which is the mysterious engine that creates attraction and marriage, either disappears or leavens with time. Speedy self-gratification, requited love, loses its intensity.
Gratification begins to disappoint.
People look for it in other places, in acquisition, in consumerism, in new sexual partners, new thrills, new experiences. If it doesn't immediately gratify, throw it away, try something new, a new car, a new sexual partner, a new wife, a new husband. Advertising, the great seducer, creates instant needs, then other needs, and on and on. Gratification means satisfaction and we are conditioned to become perpetually dissatisfied. It's probably an irreversible trend and frankly I don't know how it can be managed or even if it's right or wrong for most people.