I am going through the same thing in my relationship at the moment. 
Where this guy once couldn't stop texting me, is now too busy for me 
because of working..
Honestly,
 I think that's what guys do. They take ONE thing at a time. And they 
are horrible multitaskers. Don't even expect them to juggle multiple 
things, like work and relationship.
I keep telling my man I miss all the things he used to send and pet 
names he used to call me. His response? "Oh I don't think I'm doing 
anything different. Why are you so worried?" UGHHHH
Frankly, I'm quite worried 
right now too since he has his project and he doesn't really text me any 
lovey dovey things or call me or take out time for me. But I know how he
 can get during his project (we've been together for a year so I know) and
 well, I am trying my best to give him space to just focus on what is on
 his priority list right now.
 say you are worrying about nothing and just go on being the fun people he
 fell in love with and he will be back to normal when things in his life
 settle down. If you really love him you'll be understanding that he 
can't talk a lot and if you can't handle that, then you guys aren't mean
 to be. Got to be patient which is so hard I know.
Sometimes I am even afraid that he 
will dump me or something just because of the lack of interest that is 
visible. But maybe I am being ridiculous and so are you. Just because he doesn't show it all the time like I do, doesn't mean he doesn't love me anymore. wish you have the same mind with me ;)
Lets stay positive shall we? :)

