>>11084657easy. this is what you do op:
>do math>get hobbiesseriously, it's way better to not mix up your love life with your studies. you can meet really decent, nice and interesting people at math departments that make great friends for life.
however if you want to do mathematics long-term successfully you really should get one or two hobbies to get your mind off things. that keeps you mentally healthy and normal. you should do some sport as well. this where you can meet girls. here are some suggestions
>orchestra>choir>ballroom dancing>drama group>charity>poetry/reading clubswhatever your interests are. you can also try to convince to do one easy, but interesting lecture outside of mathematics, like some introductory linguistics, philosophy or history class.
then try to hit on girls there and if that goes horribly wrong, you can always leave the scene without fucking up your studies, still maintaining an intact social circle.