I feel unwanted... (VENT)

My Fiancé and I have been TTC for 3 months. (I’m sure I’m out this month). He is in a different state due to being in the military. He is prone to stop talking to me for periods of time. He said he would change and I had been inclined to believe and trust this. He has been doing good for almost a year. But lately he’s been short with responses and they are very few and far between. I’m lost and not sure what to do. I’m scared he’ll cheat and leave me. Any advice?

Update: he has told me in the past he’s “slept with several other women”. We broke up and have since gotten back together.

P.S He just moved to Bliss and is in processing. He has no mission right now.