My bf has suddenly changed, now that im deeply in love with him. what do i do?

my bf and i have been going out for about a yr and a half. and it was all smooth sailing, we were both into each other. we told each other we loved each other, and talked about the future a lot. my mum always told me not to get into deep so quickly but i didnt listen because i loved him so much. and then all of a sudden he got a new job and had to deal with uni. and hes time with me is very little, which is understandable. the sad thing is im not priority number one anymore, and when he has free time, he makes plans with his friends, and even told me he just' doesnt wanna hang out with me'. he yells at me all the time, i tell him im just fighting for his attention, hes become very snappy, and im so miserable, i dont have the bf i use to have. i know its just until his exams are over. but im scared this attitude is going to be natural after exams? wat should i do??? should i take him out to a special dinner? and buy him a really sentimental present, so he doesnt get over me??