SHOULD ONE'S PARTNER GO THROUGH ONE'S PHONE?

I decided to ask my colleagues this golden question '' Would you let your partner or spouse go through your phone and was shocked at the controversial response.
One responded saying '' There is truly absolutely nothing wrong for your love interest to go through your phone''

Another responded saying '' My wife can , but my girlfriend has no right to''.
Yet again another blatantly dismissed the idea saying ''Neither my wife , nor my girlfriend has the right to go through my phone, it is so wrong''.
So many others shared their views which made me come to the conclusion that a large percentage would rather not have their phone browsed by their partners.
According to Mr D , letting one's spouse or partner access to one's phones could pose harm for the relationship.
'' Women are highly sensitive he said. If she stumbles across a harmless text message or mail from another female, she could make a mountain out of a molehill when there is actually nothing, or find something to spoil her mood.
In a case of a possessive  and controlling husband, the woman could be in serious trouble for  just a simple innocent text.
He also stated that men should not let their wives know all about their activities and vice versa.
According to him , the other partner's heart may not be strong enough to carry certain kinds of information. 
With all said, a serious argument ensued and this  got me pondering .
 I wondered, if you say you love someone and obviously involved in a serious relationship with the person, why do you feel uncomfortable letting your partner see  through your phone?
Some people actually go as far a pass-wording their phones to prevent curious eyes and would even cringe if their partners layed a fist on their gadgets. 
If this  is the case, why claim to be one, have trust and  be so in love   with the other person?
My thoughts were,  if you claim you love someone so much , get to have sex with them, share precious moments with them etc,  keeping a security tab on your gadget shouldn't be the case.
 If one  has no hidden agenda, whether your partner goes through your mobile or not, it wouldn't be a disturbing issue. 
Does going through your partner's phone mean you are invading their privacy?
Shouldn't lovers and partners have unrestricted access to each others phones?