It really helps me to see how different people do things (differently!), since it helps me get perspective on what the heck I'm doing. (I sometimes feel like I have a good grasp on all of it, but sometimes feel like I'm making it up as I go.)
In any case, the card in the OP is amusing, and definitely helps me feel more secure in my situation. I think that in my secondary relationships, I'm not really at risk of getting dumped unless something breaks down fundamentally in the relationship itself. Outside factors could change the sexual nature of my relationships, I suppose, but not the personal/emotional connection and friendship.