In my opinion,it's because we trust our patner too much..
we always give in to whatever the circumstances might be...
The love that we had for our patner,is sincere and honest..from the heart..
unconditional love..respect and want him/her so badly..can't live without..
whatever it is..unfaithful,betrayed by our patner,,we get hurt but when we look at bright side.......there's always a reason for what happen..the best is be happy for him/her...not everyone inlove gets what they want..it's all fated..destiny...