This phase II trial tests how well ruxolitinib as a maintenance medication works to prevent relapse and graft-versus-host disease (GVHD) for patients who have undergone stem cell transplantation for T-cell lymphoma. GVHD is a common problem that may occur after a blood stem cell transplant. The "graft" is the donor blood cells that patients get during the transplant. The "host" is the person receiving the cells. GVHD is when the donor graft attacks and damages some of the transplant recipient's tissues. Ruxolitinib is a type of drug called a Janus kinase (JAK) inhibitor which works by decreasi