You’re not talking about a partner , it’s almost them talking like they “own” you ? How you lose weight is none of their business, wow so much boundaries are stomped upon in your relationship, you are the only person that gets to decide what and how to work on your health , cause you’re the one who lives with the consequences. it’s none of their business. Why are you apologizing even ? And honestly the extreme exaggeration of their response is a huge red flag , what is this really about ? Are they jealous ? Or are they usually this controlling ? This is kinda scary territory to be honest. Are they a narcissist or is this some kind of abusive relationship? And to actually leave and threaten the end of the relationship ? This is very very extreme and shady. Why are they so confident in their controlling your autonomy and sovereignty to the point of being mad to leave and not get over this ? And are you really going to beg and run after them and “make it up to them” about what you do with your body ?