regain love and trust in my boyfriend.

I have been in relation with my boyfriend for past two years..I had never cheated him…but there were things of past which he used to ask me and I told him all lies..now ven I have told himevrythng after lyin for two whole years he has no trust in me.he thinks I am a liar and not trustworthy.I really really love him a lot and my love for him was never a lie.my relationship is getting bad with my boyfriend.before he use to care for me a lot,liked to talk to me but now he is little interested in me.sometimes he cares but sometimes he never bothers.we are in different places so we mainly communicate through phone and internet.its mostly that I call him from phone because its expensive from him.I m studying in malaysia while he is in a college in singapore.its even expensive for me to call but just because I want to tak to him..keep mising him so I call him..but now these days he is somwhat not so caring and loving and is only wanting to have phone sex,and cum to meet me to have sex.I want to have sex after I get married to him.I m 20 and as well my boyfriend is also 20.we are planning to get married later after finishing with studies.but his behavior and love towards me is decreasing.what should I do to make my relationship again go very healthy ans with love and trust.