How to recover from relationship fatigue?

So I've ever had to spend extended periods of time with a significant other - my longest relationship was in high school and I am very independent. But for me and my boyfriend it was cheaper (almost $1000 cheaper) to live together for 3 1/2 months. But, like I said, cause I've never spent so long with one person, I'm getting tired. I feel more like a roommate, and sex feels like a chore. I get almost no alone time and we rarely go on dates because we're still on a tight budget. How can I relieve this feeling?