Oh god why is this so hard?.....
Because, if it was *that* easy/simple everyone would be walking around with no excess weight, no weight related health issues and all "diet" clubs/foods/books/franchises would be either bankrupt or obsolete
Because, if it was *easy*, there would be no challenge to it which, in turn, means no sense of achievement and the risk of stunted personal growth!
We learn a lot about
ourselves when we strive for something which is a bit of a challenge: our strengths, our weaknesses, our potential, our limitations ... even who are true friends in life are and if, just if, we may actually be our own worst enemy!
I can understand that you are feeling let down by your fiancée, someone who offered to support you and do this with you - but, to be really fair, unless your fiancée is motivated to lose weight for himself, then, even with the best intentions, he will not be as committed as you feel he should be and therefore cannot give you the full support you feel you need from him.
Equally, unless he is in need of losing weight (and a desire for it!), why would you need him to "promise" to do this with you? This is about *you*: y
our intentions to lose weight;
your challenge to do it following a SW plan and
your journey along the way.
The honest, eye opening, no punches pulled truth is:-
- you are going to have good days
- great days,
- in between days,
- 'meh' days and
- some very difficult days of temptations, cravings, mood related eating and outright Arggh! days.
They
will happen regardless of whether you are:-
- married,
- engaged,
- single,
- female,
- male,
- young,
- old,
- blond,
- brunette,
- working,
- unemployed,
- parent,
- non-parent,
- 1lb or many lbs over weight,
- active,
- inactive,
- hairy,
- bald,
- spotty,
- freckly,
- tall,
- short,
- pink,
- blue,
- brown,
- yellow
- or tartan!!
So, now we are clear: this is *your* decision/journey + you
are going to have bad times/days
I'll repeat, just so you don't lose track: this is *your* decision/journey + you
are going to have bad times/days

Once you accept that, then you will be half way there :bighug:
Now you also need to have in place a strategy for coping with those bad times/days.
- he decided it would be better for us to go and have a steak - I think you could benefit from learning some "assertiveness" techniques for those occasions where fiancée changes *his* mind (and you follow along regardless) because where you go "together" should be a "joint" decision, not a game of follow the leader
- he decided to buy chocolate as he really fancied it - And why shouldn't he?
What SW treat did you really fancy that you could have bought? A special fruit, maybe (something you wouldn't normally "treat" yourself to?) A particular brand of FF yogurt you wouldn't usually eat? Something from within the Syn list, perhaps? 
- he brought out the Doritos. - And why shouldn't' he?
You should also have been able to whip out a SW style snack of your own (with a little forward planning - after all, he had 'planned' Doritos for eating at some point in time because they were available
)
Well done on waking up and rewiring your thinking so that today, you are starting afresh. That is great news!!!! :clap: :clap: :clap: But, please begin afresh with some strategies in place for those bad times/days or, you will simply end up back in your room crying in frustration (and guilt!) and wondering how it all went wrong again :bighug:
Remember those two truths:
- This is *your* journey
- You *will* have bad times/days
And the 3rd one is:
3. You will be as successful in your journey as you make up your mind to be
Good luck
