A locked cabinet has been working wonders for me. It's hard to restrict everyone in the house to my dietary needs, but it's also hard to live in a house where unhealthy temptation is in every corner.

Give her the key and ask her to lock all her junk food up. It works.

I am not saying that this happened to me ;) But if I was facing a choice between (eventually) getting Metabolic syndrome and a having to find a new GF, I would definitely not choose to get metabolic syndrome :)

Yeah and frankly it's a bit of a red flag to me now whenever I see one partner sabotage (whether intention or not) the achievements of their significant other. That's not to say that their girlfriend is lacking moral high ground, but rather it may not be an optimal coupling. A good partner will naturally encourage you to be your best self and you will encourage them similarly.

This. The definition of a partner over time shifted from someone who does stuff with me and eats dinner with me and watches movies to someone who understands my goals and dreams and supports and pushes me to get there and vice-versa.

Life is too short.