Would u be worried if your dp acted like this before going away for three nights for work?:
Much more distant with you, gone from cuddling, lovey dovey to sitting far apart on sofa on iPad or phone (not exactly doing something suspicious -can just see he's on eBay or playing games)
Starting to accuse you with going with other men. This isn't uncommon for him/the relationship but hasn't done it for awhile. Just randomly starts saying bet you've been with more than you've told me about" them basically calling you a liar
Bit more snappy with you, I.e "can't you do this right?" Kinda thing
Only mentioning he's going away on train when he usually has a works car, also usually goes away with a secondary person at work but not this time? Sounds legit enough but would it worry you?