I find the key to longer term relationships are like subtly throwing yourself in on the problems. Like my gf at one point years ago started to develop those upside down triangle arms. Like when you know a person(even male) wears a sleeveless shirt and the shoulder area is the widest and it gets slimer down the arms...fuck that man, I have to have a gf/wife I find attractive....cause guess what will happen in time if I don't find my SO attractive....
I would just say stuff like 'hey we should kind start watching what we eat, we are getting older and should be taking better care of ourselves.' and if I'm met with 'I don't know what your talking about', well then I will have to point up what I've called 'upside down triangle arm'. I hold my gf to the same rule as I hold myself just a female version....my stomach shouldn't go beyond my chest and same with her( this gives her even more leeway).
Cause guess what will happen if I don't speak up in a calculated manner? Stupid family and friends, 'your so small'....coming from the mouth of every fat family member.
And for anyone who says 'your an a-whole'...'you shouldn't be saying that stuff'....b.s. you wanna be with someone the rest of your life, you are both accountable to each other. Find a form of exercise and food alternatives that work for you both. For my gf and I for example, she goes to pilates and random hikes and bike rides, I go with her on the later two. We find lower calorie pizzas that are flat crust instead of just binging out. You have to put effort in.
I've met a handful of people in my life who tell me their SO doesn't find them attractive since they gained weight....whelp sucks for you, I don't want to be involved in that dynamic.