A recent study published in the Journal of Consumer Psychology, “experiencing guilt from keeping a consumer behavior a secret, even one as mundane as secretly eating pizza, will lead individuals to want to do something positive for the relationship.” In other words, if you do something behind your partner’s back, it makes your relationship stronger.
Obviously that doesn't include ALL secrets... like cheating which will hurt the relationship.
But the researchers say that “Secret Consumer Behavior,” was something that 90% of the study participants had done.
Source: Fox News