when you cannot go in your room because your room mate is having sex

A Bloomer is someone with a bright outlook on life who is optimistic in nature. Bloomer's frolic in every opportunity to be happy and try to make the most out of life. The opposite of a Bloomer is a Doomer. The term Bloomer originated specifically as a counter to the Doomer on sites especially like 4Chan.

To be exiled from your appartment or room because your roomate is having sex with someone.

When politely asked or forced from one's room in order to create the private atmosphere most roommates need for coitus with their special friends. Incidentally, it is what I am right now.

refering to "exiling" your roomate (usually in a college setting) from his/her room so that you can engage in sexual activity without voyeurism.

The past-participle of the verb sexile.
To be banished from one's room (most often, a single-space dormitory room) so that the roommate may engage in private sexual intercourse. Generally speaking, sodomy, cunninglingus, fellatio, and most forms of foreplay consitute grounds for sexiling.

To be "exiled" or banished from the dorm while it is being used by a roommate wanting privacy for (often overnight) sexual activity.
It is a common phenomenon at college, often done willingly by arrangement, which may include telltale signs to show the room is being used (i.e. a strategically placed sock or tie). Where sexiling becomes too regular and inconsiderate, the solution is another Urban Dictionary favourite = Cockblocking.