Need advice - loss of attraction

Hi Poly Community!

Been confronted with some difficult feelings, and was wondering if anyone had any advice or life experience with a similar situation, a d hopefully get some positive results!

I'm deeply in love and attracted to my(NB27) partner(F27) of 8.5 years, engaged for 6 and her poly for 3 years with myself being monogamous.

My partner has told me that she does not find me attractive, and after talking about it we worked out it probably has been the case for 2 years. She is in love with me, but now struggles to reciprocate affection, but has earnestly told me she wants to find the attraction again, and if she cannot, has no desire to leave the relationship, and wants to continue to be intimate, but does not actively desire it.

She is still actively seeking new relationships with people who's body types she is attracted to.

I am motovated to improve myself and work on the areas we have identified as, best put, unattractive (physical appearance no longer suits her thanks to putting on weight)

Does anyone have any advice on how to either deal with that shock and pretty miserable thoughts of finding out your most beloved no longer finds you attractive; or any advice on what else we can do to improve things, or to help discuss with her my needs without making her feel pressured.

As it stands we are both deeply committed, but as the momogamous one, I am struggling to feel 100% safe and secure in the relationship - hopefully just the shock and will blow over soon.