I need some mature advice please?

maybe my question is stupid but i want to know what you think about this.My Boyfriend is in the army and he went to Iraq 3 months ago.Since a month now he is the UK for a course (we both live in Germany) and he will stay till there the end of the month.Before he has been deployed,he was busy all the time and irritable sometimes.I felt neglected and we use to quarrel about that.Now is in the Uk but he comes to germany from time to time.Since he is back,his behavior change.Whenever he comes to Germany,he will call to say that he is back.Now he is the one who want to see me all the time and he cares more.what makes him a change?my friends think that maybe he is cheating on me and it's the reason why he changed.