Loneliness despite a companion

I care about my boyfriend but,though he loves me and is very happy and content with me, I often feel sad and lonely... Like I am not supposed to be with him.. Such thoughts make me feel terribly guilty and ashamed.. But how can I shake off this feeling? I tried very hard to be honest and fair to him and explained him all this.. But he was hurt and now he is very insecure about me and always blackmails me with threats of harming himself. What do I do? Is it fair for either of us to be with each other this way?

maybe you feel sad and lonely because he somehow somewhere maybe doesn't love himself enough - and counts on you to make him feel loved : so there is a lot of pressure on you - all this may be unconscious but something in you could tell you there's something "not right" this seems to receive confirmation with him threatening you with harming himself - as soon as he get's insecure about you this should not be accepted as something healthy - not for you and even less so for him : why does he want to harm himself ? has he done it before ? how ? this issue is more something that concerns him then you it seems : he has to find out what's "wrong" with him and why - you can not really help him with this - maybe he shoud see a counselor or therapist to look more deeply into this don't feel too concerned - give yourself permission to "take a backseat" emotionally so you can feel more balanced and overall better ask him - quietly and calmy - why he blackmails you with harming himself - and if he feels that's ok

But he says that I am being harsh and "heartless" when I told him what bothered me and how I was feeling, even though I assured him that I loved him, which I really do...at least as a best friend... He wasn't like this before..and I want to help him.. And when I told him how very much I hated to hear his threats, he promised to never say such things again... But somehow he "forgets" sometimes..

yes ,may be he is ur best frd but u dont idealise him as ur lover. Tell him i can always b wid u as a frd but not as a lover... how much do u know him,how far have the relationship gone>?