Swaddling nightmare...

We have swaddled since day one. For night time that is. For the past month I have been leaving an arm out. The last two nights its been both arms but still tight around body. Such bad sleeps! Last night he was wide awake so in a cloud of exhaustion i swaddled both arms gave him a snuggle then put him down eyes open. He has not moved a muscle. Hes sleeping sooooo well like this hasnt happened for over a month. So now what should i do i cant swaddle him forever...any moms have any techniques that worked well. Im trying to avoid buying products ie Merlin sleep sac but I guess ill have to if I cant transition him.