I was never in a long term relationship when I was skinny. Pre meds. Since I have been extremely fat, partially due to meds, I have been in 2 longterm relationships of about 5 years each. I entered both of those relationships fat. Without being too graphic I will say sex is not as beautiful as it would be if both of us were skinny. But love came and sex came, and actually the sex was quite good. I tend to focus on my partner's face and small sections of her body rather than her body overall. Honestly, I think the sex would have been much hotter had we both been skinny. But the love was there and there was passion. So I guess you take what you can get and hope for the best.