Re: my daughter
One positive aspect is that she's working out regularly. Exercise provides many health benefits in addition to helping with weight loss. Even if she never loses a pound, working out will make her healthier. She will improve her cardiovascular system, strengthen her bones and all connective tissues, improve organ function, decrease risk for diabetes, and many more benefits. She will also look better. Her skin will appear healthier and her posture will be better.
She may always struggle with her weight, but the health impacts of that can be minimized if she continues to work out. Being her workout partner is probably a huge motivation boost for her to keep going. Keep doing that as much as you can. Chances are, she's much more likely to go more often and workout longer with you than if she had to do it herself.