There's a difference between a lone stoic tear and ugly crying. Women need stability from a man, displaying instability is going to disgust her old lizard brain. Proverbially if you were a house she sees this as a leaky rough, and she can't fix it. A lone stoic tear at a funeral or wedding or after a major terror attack is only going to humanize you show your restraint and demonstrate that you have emotions, she will characterize you a bit though unless you're with a psycho the worst consequence is that she'll probably try to talk more about her feelings, this is a catch 22 and will evolve into new shit tests though. If you sob or worse she will lose her image of you as emotionally stable and independent. I have a leaky tear duct and have genuinely had to deal with girlfriends thinking I'm crying and shit testing me over it. I have a rule to never let a woman I want to sit to my left. The bad tear duct is on the left and also I'm betting on a subconscious association between driving a car and authority/risk dynamics.