Grapefruit digestion question

arabeque

Hello, I'm pretty much a "fruitist" (except for my explosions/sudden, big cravings), which means I love fruits etc.
I eat grapefruits a lot, too, but I recently came to see that.... I don't seem to digest them well: sometimes my poo (excuse me) has grapefruit all around. So I'm wondering if there's some problem, or maybe that grapefruits just are like that, OR maybe this happens only after a portion of laxative tea (Sennae folium, which I usually use after my binge days).
Sorry if gross, I'm just curious (I mean, who wouldn't be curious about some red poop)