What can you do?
1. Talk to your roommate. If you are feeling this way, it is likely that your roommate shares the sentiment. If you talk it out, you may find some middle ground or can make plans for one roommate to move out and find a someone to sublet. You may be able to locate a community mediator or university ombudsman to help facilitate conversation and agreement.
2. If your roommate is a co-tenant... If both of your names are on the lease, you are co-tenants and have equal right to remain in the lease. This means you likely won't be able to evict a roommate.
3. If your roommate is sublessee... If you subletted a room to your roommate you may be able to use eviction procedures to legally disassociate your roommate from the apartment, and the lease.
4. Beware of "joint and several" liability. If you look at the boiler plate language on your lease you may notice a clause that states that co-tenants are "jointly and severally liable" for making rent payments. This means that each tenant is technically liable to pay the entire portion of the rent. If a co-tenant does not pay their portion of rent then fellow roommates may have a legal action for non-payment.
5. Plan ahead for next time. Oftentimes written roommate agreements may not be necessary, however, if you are coming off of a bad roommate ordeal you may consider one for next time. You can discuss issues such rent payment, shared household responsibilities, shared parking, quiet time, and guests. You can see a sample written roommate agreement here.