When do you no its the right time to let go ??? please help?

me and my gf have been together nealy a year, i love her more than anything and would do anything for her to be happy but i dont no what to do no more. i dont get to see her alot witch isnt realy her fault but i have always planned these romantic days for me and her but evry time she hasent been able to come and its been hurting me and now im startin to wonder if i can carry on but the thought of her with someone else kills me i love her but im getin hurt by not seein her she says it bothers her to. for the 1st couple of months she realy showed hw much i ment 2 her but now im not to sure. sometimes i feel that i cant go through with not seein her 4 a week but others i can bare to lose her so how do u no what will hurt more stayin or leavin and risk losin the girl you love?