Loving married co worker.. should i tell her?

Hi all,
I cannot bear it anymore.. it has become obsessed and so engrossed..
i found one of my new comer office girl sad.. i did my best to make her happy and talking. i was patiently listening and made her talk and entertained her in various ways.. it was not for anything but rather helping a paining heart.. nothing more.

it is some time and seems she has overcome her problems and started spreading her charm.. she is not flirting sticks with marriage. but seems inside of her still there is some sadness. she was very comfortable with me and was speaking with me (me only it was my pride that whoever says ugly jokes she wont listen to)

now my problem is i am becoming very unhappy and looks odd and grudge these days
it was so nice days earlier when we had wonderful period is no longer there. she looks happy and talks with everyone .enjoying.. she is very communicative and is very good listener has a good voice and think but good physique. she is so innocent that poeple can exploit her

but i am in agony and couldnt tell anyone around that i feel this inside. she understands that i am not feeling well. passionately stays with me but still could answer throw jokes and others what i feel is a kind of possessive


it is not that i want something from her.. but i want our relation to keep going.. just talking is enough..
but i fear she might stop doing the same soon. it is because she is mingling with people who i consider against my principle.. (or say i am angry at them) it is just three of them. one who always stands near her another trying the same but a slower manner and the other through ugly jokes and pleasant faces. (sad that three of them are married and i am single). i dont own her but i feel i deserve more attention.

the thing that pricks me now is whether i should tell her what i feel and still not demanding any actions from her..
should i proceed please advice