Love Quotes in Eclipse

How we cite our quotes: (chapter.paragraph)

Quote #10

And then quite distinctly I felt the splintering along the fissure line in my heart as the smaller part wrenched itself away from the whole. (23.276)

Does that mean that your heart can't take loving two people at the same time? Or is it more a matter of morality and cultural tradition to choose to be with only one person?