Breaking a lease

Looking to break my lease because of an international move, I still have until September on my lease. I tried to speak to the building manager about exploring my options but he said if I break it I’ll have to pay half a month or a full month. Took a look at my lease and it’s a general RTB agreement and doesn’t say anything like that in there. What’s the best option? If I break it, I’ve noticed they don’t typically put apartments on the market until after move out and I have until May to run with (but I doubt they’ll put it on the market before).