Sex at Dawn has become the first thing that pops into my mind when I hear someone ask, "Why am I not enough?" or, "How can I ease my spouse's/partner's feelings that he's/she's not enough?" Sex at Dawn establishes human tendencies that have nothing to do with whether this or that partner is "enough." We just tend to fall in love with more than one person -- that's all.
Anyway, I checked out your link and it looks alright by me.