Need help!

Okay so my partner is in the Army and he's away atm, I'm 32 weeks pregnant and he's due back 4 days before my due date.

Anyway we message every day, but the past few days he's completely changed, he reads my messages and doesn't reply until like 30 mins after reading them. He goes to the gym and always messages me whilst he's there but hasn't been messaging me at all and he's there for 3 hours?

He has just completely changed so I asked him if anything was wrong as he kept putting songs on his social media about feelings ect (which he only ever does if he's upset/thinking about stuff) his reply was "narrrrr I'm fine me"

Which was when I deffo knew something was wrong as he normally reassures me everything is okay and he never uses the word "narrrrr" but instead it was just that reply then shortly after he said he was going to bed and put "love you"

We have this thing that we will never say "love you" without the 'I' as we feel it has no meaning to it. So I asked him why he said it in that way and he replied "I forgot to put the I okay" which is something he has never EVER done. He keeps saying he's fine but I know him through and through and I know he isn't

Now he's asleep and I'm laid in bed thinking he's fallen out of love with me and speaking to someone else. He's Also changed all of his social media account passwords too but I've kept all of mine the same. With him working away if either of us are worrying we like to quickly check but he's changed it?

I'm going out of my mind here😫