Need encouragement

Sooo ttc for almost 6 months now and getting a little discouraged... It doesn't help that my husband is a Marine and at the beginning of July he will be leaving for a little over 4 months for some training exercise :-( he told me yesterday that sex is kinda feeling like a chore, while yes still enjoyable it just feels really planned... We missed 3 days of my fertility week including my peak day. I just feel that our ttc window is starting to close and while I know he wants another baby just as much as I do I can't help but feel a little frustrated with him for his comments and the situation were in....