You don't have to shift too many things around in your character history to accommodate me ;).  The two characters could have met during undergrad.<br/><br/>What if they were lab/study partners?<br/><br/>I see them as not having many things in common except their coursework, with their friendship manifesting gradually.  There would be a sexual subtext to their friendship which unfortunately never develops on account of Michael's hectic superhero schedule.  Towards the end of their friendship, Michael's seemingly unreliable and always getting injured in accidents or assaults.  His excuses are always flaky and unbelievable.  He is never there when you need him.  The sensitive, good-looking guy anyone could talk to became despondent, taciturn and moody because the stress of his decisions and his injuries were emotionally overwhelming.  I also see Michael sleeping with Nicole's best friend after a night of drinking (read: his only night of ever drinking), which might further wedge the two apart.  Once Nicole graduated, deleting Michael from her contacts was simple.  (Please don't feel pressured into accepting this scenario, it's just a suggestion).<br/><br/>I like the paths of characterization you described, but Arrow wouldn't be depressed if he was defeated by Nicole.  I think he'd be completely perplexed.