General

Let me begin with saying I am in a long term, committed relationship with my girlfriend of 5 years. This will be a long post with a tlr.

Over the past 6 months or so she has lost a fairly significant amount of weight-- citing an urge to get abs. Simultaneously, our sex life has taken a noticable dive due to her weight in that I found her far more attractive with the extra pounds. This is something that I have not discussed with her.

I have discussed in the past with her about my fetishs, but she did not receive them very well. Although she was understanding and gentle, she had absolutely no desire to try anything.

She recently approached me acknowledging our lack of intimacy and asked for a way to include my fetish.

Does anyone have suggestions on how to incorporate a weight gain, and belly fetish to a bedroom where the partner does not have the fetish? I'm hesitant to suggest anything too invasive due to her self esteem and body image problems.

Thank you all so much. This community rocks and is so supportive.

Tl;dr
Girlfriend lost weight and I find her less attractive. Any suggestions on how to incorporate a weight gain / belly fetish to someone that doesn't have it?

Oof. I get That. Had a similar situation before, but things ended before we could resolve it. I'm posting here also curious as to an answer to your question. I hope things work out!

I really wish the best for your relationship, but I was in a similar situation with my ex.
It did not end well, but we were also in a distance relationship due to her moving out for college. Maybe I also let her fuck others guys so she could satisfy her constant urge of sex, oopsie!

The issue is I don't find myself gaining erotic at all. I'm willing to give everything for her, but I'm not sure what she's willing to give back. It's a really tough situation given that my sexual proclivity are based on her sacrifices.

I'll bring that up to her. Executed in the right way, like you said, it doesn't have to be a gaining experience. Thank you!

Agree - if you can avoid any "your body isn't turning me on" chat, that could be helpful. Feeling like you'll love her at any size is important.
What is it about this stuff that gets you going?
Bloating/overeating? Try with water/fruit/air pump.
Tight clothes? Use smaller ones.
When my o/h has lost weight in the past, It's been easy enough to remember what it was like at the old weight, and thinking about sliding back to that was quite fun.
What about any kinks she has?

Telling your partner that she's not fat enough for you and that you would like her to gain is not ok if she's not into it.

She has some that we have indulged in in the past. I'm not sure if that has made her more inclined to try my kinks out. Hers are much less demanding then these damned ones.