Why Does She Stay.???

i never really understood why women stay in realtionships when they know they are loving the other person more than they are being loved ... but in return i never understood why men continued to entertain the idea of beingin a realtionship with someone they know they really dont want to be with... its like why keep them on the side when you could just move on.??? but i guess thats easy to do when she has decided to be helpless ... and has made it apparent that she cant move on and doesnt want to move on ... idk recently ive seen more and more girls get in realtionships that are good in the begining and take a turn somewhere near bad and have fallen off the cliff past worse and theyre continuing to HOLD ON to when they were driving down a street called nice ... knowing that they can no longer make a U-turn ... now i cant sit here and act like i dont understand because i was that girl once ... taking frequent strolls down memory lane and thinking about the way things USED TO be ... attempting to get him to be the person i fell in love with oh so long ago ... but people grow and change ... whether it be for the good or bad, the change and dont stay the same ... so to my ladies that have found themselves in this situation when is enough enough.?? when do you decide that you love yourself more.?? when are you going to stop holding on to the USED TO BE'S and allow yourself to move on and that person to do them ... even if its bad for them.??