I think it's human nature to sometimes compare yourself to others. Whether your friends, family, a partner or strangers I find myself doing this sometimes when I am a little insecure and I think it may be one of the most detrimental things to your self-esteem.
I see a beautiful girl in a trendy dress which would only suit a size 6 model and I decide I like that style.. I want to experiment with it.
I go to the shops and try on a similar dress but I have bigger hips and smaller boobs and this dress looks like it's for a maternity collection on me and I decide that's it! I won't eat until I fits me.
I love food and I know this feeling of repulsion will pass.
The point is, it's not the dress or the girl, its me.
I may not be able to wear one particular dress but I can accentuate my hips and waist in a flattering way that would look terrible on that girl. Not all clothes look good on skinny. In fact a lot of fitted tailored clothes suit curvier women. So instead of not eating (again how ridiculous) and mind you I tend to binge if I don't eat regularly and healthily. Instead of disrespecting my body by neglecting it I now understand what styles suit me and what don't. I know that if I have a moment of insecurity its healthier to feed it with love rather than comparing myself to the size 6 girl.
I will never be a size 6 and finally at 27 I have come to peace with that. In saying that I want to be the healthiest most beautiful version of myself. I work out 3-4 times a week. I eat well on most days and I laugh a lot.
Don't breed insecurity by comparing yourself to anyone else. Not to their body shape/career or how wonderful their boyfriend is. Everyone has their "stuff" just worry about keeping yourself happy.
These thoughts will slip up from time to time and remember you need to step back and look at the whole picture and get perspective.
Be kind to yourself x