okay heres a hypothetical... things are going well and what not when suddenly Todd (random name) appears in the picture... now Todd is her coworker/friend from school/friend of a friend/girlfriends friend whatever. It all seems kinda innocent, "oh Todd was telling me about this bullshit blah blah blah" the conversation is unimportant, what is important however is the seed of doubt... suddenly that name is in ur head... TODDDDDDD, TODDDDDD... Todd isnt just her coworker/friend from school/friend of a friend/girlfriends friend he is now your competition... but no your current girlfriend would never do that to you... ehhhhh!!! news flash she already did... now the seed germinates into roots, a stem and a big ol fucking thorn but no pretty flower... next thing you know she comes to you with a sob story about how things arent working out and that she met someone else... TODDDDDD, TODDDDD the innocent coworker/friend from school/friend of a friend/girlfriends friend... see the picture?