So I just skimmed this thick, academic book full of Calvin's matchmaking letters and found some interesting nuggets.
1. Calvin played matchmaker a lot in Geneva, taking many personal hits for making recommendations against someone or other's child's particular suit.
2. Calvin recommended that couples get to know one another before committing to marriage. "Love requires previous acquaintance." This is of the "whoa, slow down, there, young buck" variety. But he made wedding plans for himself before meeting a potential bride. It fell through, and he was discouraged. Then he married someone else 2 months later.
3. Geneva had strict rules about getting married within 6 weeks of being engaged, to avoid "the perilous interval," as Chesterton called it. Those who delayed were admonished publicly by the session, and eventually "compelled to celebrate" marriage. Pre-marital sex was eventually censured publicly by not allowing flowers at the ceremony, and by announcing the sin at their wedding ceremony! Whoa.