Dieting in a pack is supposedly motivating. Not sure however that the evidence supports this. Definitely not on the basis of the recent few days.
Thing is - dieting goals between the various members of the group can be quite different in terms of scale and ambition. If your group compromises a bunch of Karen Carpenters and then you, the 21st century' version of the blob, then being in the same group is dangerous for everyone.
So stick to your own plan - ignore the rest. Take the time only to gloat if they're doing nowhere near as well as you.
So true, I hope not to find all the kilos my love loses
Couples are all about sharing. Good on you.