He might not be happy with the other party now, you never know.
You can make a change for someone you like, why not? Life is short,
treasure those that are with you. I presume you are a year 3
student since you said Calvin like to oogle at you.. School is
ending for you, chances that you will see him again are slim. Even
if scare of worsening the relationship, its only for a short time
only. Taking a try at it is alot more than not trying it. Do it
else you will regret it.
Some more, he is going army soon, just go before he gets called
into army. Scully he becomes a gay after entering the army? You
never know whether is he happy with his present relationship or
not... GO AND TRY!!!!