system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are the main reasons for why dating/relationships have changed so much over the last 100 years?

From arranged marriages in the early 1900s to quick courtships in the 30s-60s and high divorce rates in the 21st century, what are the main factors that cause such a substantial change in how humans have romantic relationships?
gpt
By *far* the biggest reasons are (1) birth control, and (2) women's rights.

Birth control means that casual dating, and even casual sex, is not very likely to lead to a pregnancy. That makes it much less important to avoid.

Women's rights mean that a woman doesn't *have to* get married in order to have a good life. That hugely reduces the pressure to either "marry this one or move along".