I would like to lose a little weight but my partner refuses to help me. What can i do?

I use to go to the gym and began to lose weight until I was told to stop. I really want to lose before I have health problems. He seems to have a problem with me being slimmer in case I become attractive to someone else. He doesn't tell me I'm attractive until I feel bloated and fat. How can I lose about 8-9 kgs without him realising that I'm doing it?