I'm considerably heavier now than I was when I met my SO. Yes, a lot of that is due to my little boy, but some of it is because we got comfortable and cosy, and it just crept up.
This is a really delicate situation. I think your best bet would be to enrol both of you in a fun activity that you'll both enjoy - ice skating, dance classes, whatever. Pitch it to your BF as something fun to do together.
The other thing is this - do you think he's unaware that he's gained weight?
Mummy's Little Dude!
