Chemistry, or lack thereof.....

Have u ever not shared chemistry with someone, not clicked with them,not found any bit of anything in common with them & even if there was, what does it matter, the point is, u share no chemistry, u just can't stand them, their presence, their voice, their jokes, their aura...everything. What am i asking, of course u have. How do u deal with such situations? Do u force urself, do u manage to share a room with them, do u manage to force urself to laugh at their unfunny jokes, coz lets face it, when u don't click with someone, any jokes they attempt to share will never be funny. Does the problem lie with the person u don't share chemistry with or is it with u who shares no chemistry with them that has the problem? Is it easier to pretend? Can u pretend to laugh when deep down u really don't find the "funny"? Besides common courtesy of being polite to them, do u owe them anything beyond that? Should u force a friendship with someone u don't click with? Should u be blamed for not going further than demonstrate common courtesy to someone u feel u can never be friends with if called upon to do so? Should it take much effort to click with someone? Is there need for something to have happened to cause the lack of chemistry or is it possible for it to just be automatic? Mmmmhhhhh, ok clearly i don't have the answers. What i know is, it happens, sometimes the chemistry just isn't there.......U shouldn't have to force it, if its not there, it just isn't there.......