Because they're too much of a coward to tell their partner their needs/find out their partner's needs, so their relationship suffers or becomes one-sided.
they're unstable emotionally with their undetected flaws not resolved. it's like an insecurity thing.
- They genuinely fall for someone else<br />
- They think their b/f or g/f is going to dump them so they do it first<br />
- They are unhappy & fear loneliness<br />
Not an exhustive list......
Because people feel inadequate with themselves, and to feel more adequate they look to dating. When dating no longer inspires, they look for more dating. Rather than inward.
b/f and g/f are temporary states at most it indicates a mild interest
mostly selfishness based on a false sense of entitlement