Libido loss?

So my boyfriend and I have been going steady for quite some time now and so far I have notice something alarming. My boyfriend no long initiated sex with me like he used to. I've talked to him about it and he always becomes self conscious. I personally have a pretty high sex drive and he can no longer keep up. Due to this issue my self esteem has taken a drastic nose dive. I just want to know if this is normal?