Sex...or the lack of!

My husband and I have been married for 5 months and TTC for almost 3 months. We talked a lot about trying for a baby prior to coming off contraception. In the almost 3 months of trying we've only had sex a few times, this isn't unusual but I was hoping he would at least try a bit harder to help us conceive. I don't know what to do to get him to try harder - I've tried everything (including trying to instigate) I can think of and nothing's working!! Help!!