Caught by Roommate

I stay in a hall of residence in university and always took a double room because it is cheaper. We can choose our roommates but I always left it to random chance. In my second year, I was assigned a Malaysian-Chinese. We got along pretty well - he was never noisy, always cleaned his part of the room weekly and is also pretty cute though he's quite short. One thing, however, is that he seems quite shy. Usually hall guys will wrap a towel after showering and change back our the room, but he always changed inside the shower stall. At night, he would sleep in a T-shirt and pyjama bottoms while I slept in my boxers. I usually waited till he went to sleep before I masturbated. The toilet is so old and decrepit that there's no way I'm going to do it there! Our room's window faces the foot of a hill so no one could peek in, but moonlight can shine through. Our beds are in parallel, with about a metre gap in between. One night I was jerking off as usual with my boxers pulled down to my ankles, trying to be as quiet as possible. Suddenly, my roomie got up from his bed and left the room. I was damn shocked, I was so sure he was asleep. In the moonlight it was obvious what I was doing. My erection wilted and I quickly pulled up my boxers. About five minutes later, he came back. There was a bit of an awkward silence. Then I asked him, "You went toilet ah?". He said yah. A while later I ventured, Me: Uhm... sorry I thought you were asleep. Him: Nah, I saw you do that before but didn't want to disturb. Just now I had to go pee. Me: Oh... (blushing heavily in the dark). Erm, can I ask you a question? How come you don't need to masturbate? I mean, you always sleep before me. Him: Ah... sometimes I do it in the afternoon when you are not in the room. Me: Oh, I can't because my schedule is always packed. Science courses have lots of lab sessions. Him: Haha lucky I'm in Arts... Oh, you can finish lah, I've seen your body naked and shooting before liao. Me: Oh... After a while of hesitation, I pulled down my boxers and continued pumping. As I didn't have to stay quiet, and I know that he's there knowing what I'm doing, I cummed quickly and it was one of my most explosive orgasms. I was afraid he'd spread the word but he kept his silence. The next night, once the lights are out I asked him, "Do you mind if I mast? I mean, since you've seen me already there's no point in waiting for you to sleep." He said he didn't mind, so I carried on. A few nights later, I heard a rustling sound from his bed. I looked over, and he had also pulled down his pants and was masturbating. We jerked off side by side in relative silence, but gasps and sharp breaths were especially loud in the silence of the night. I was looking at him from the corner of my eye, it was a very "chaste" type of masturbation for us - no nipple pinching, no roving hands, just one hand on dick and the other laying by the side. He came first with a visible shudder, and I came soon after. Wordlessly I passed him a few pieces of tissue from my table nearby which he used. From then on he became more relaxed. He started changing in the room and he started sleeping shirtless and in shorts. We also went out for midnight supper at another hall together. At night, after the lights are off, whoever is in need would just relief ourselves without having to wait for the other person to fall asleep. Sometimes we did it together, sometimes solo.