No libido

Patient: When my boyfriend and I began dating, he was interested in having sex all of the time. We’d have sex at least twice a day. After dating a year, we got an apartment together. For the last two, his sexual desire has plummeted. In the last six or so months, he has lost complete interest in me. Sexy lingerie and flirtation don’t lead to anything and he seems to have lost complete interest in him.I am twenty one now and he is twenty three.We finally discussed it a couple of nights ago and he says that it isn’t me, and that he has lost all sexual urges. He said he doesn’t even masturbate anymore and it can sometimes scare him because he doesn’t feel that it’s normal. What can we do?