Marnie is apparently really attractive?

[FireLighter]

So Lewis and Marnie seem to be in a secret relationship, but also at the flower dance in the spring, Marlon comments on her, saying "she's looking fine." or something like that.

[Jonathan J. O'Neill]

She doesn't look bad. She's a little chunky but it's no problem for me.

Honestly, I wish all the villagers were romanceable just to give us the freedom to marry our favorite person and destroy marriages. Robin, you will be mine one day.

[0ptimistPrime (the Gray)]

Maybe she is, maybe she isn't. Beauty is subjective.
To be fair, she could never shower or wash her clothes and two people could still be into her. There's nothing conclusive about it.

Originally posted by Jonathan J. O'Neill:

Honestly, I wish all the villagers were romanceable just to give us the freedom to marry our favorite person and destroy marriages. Robin, you will be mine one day.

I wholeheartedly concur. I'm all about Jodi.
I'd massively (and happily) ruin Sam's family.

[dino_inc]

Marnie's profile picture in dialogue is far better than her sprite in the normal game view, so I think she is intended to be attractive.

[Grimm Turd]

https://stardewvalleywiki.com/mediawiki/images/b/b0/SecretNote11.png

Marnie is a rancher and most of that farm life is probably muscle under them t.h.i.c.c., birthin' hips.