Social life Ann Arbor (UMichigan) vs. New Haven (Yale)

[StuartLittle]

Hello everyone, I was wondering if anyone could speak about the social life as a graduate student at Yale.

I am currently split between Michigan Ann Arbor and Yale. I studied as an undergrad exchange student at Ann Arbor and I absolutely loved it and it seems that nothing beats it. Even my Biostats dept. at Michigan is larger and people are friendly and graduate students seem sociable. (I am at a point where I want to find a serious partner  so the opportunities to meet people are important)

Where as for New Haven, I have been told and I observe that it is not like Ann Arbor. What is the social life like at Yale? 

My mental health is an extremely important factor that will contribute to the success of grad school.