I'm worried that I'm losing my boyfriend.

So me and my boyfriend have been together for 2 years, we're 21 and 90% of the time are really good. Recently we had an argument about where to go on holiday, we disagreed with the location and we ended up having a huge fight and decided to leave it because neither of us wanted to continue the argument. (I was being the compromising one, being kind and loving and saying I don't care where we go I just want to be with you - he had a really bad temper and was being nasty.)

Just for context, up until now he rarely used to see friends and was always focused on his studies, and he used to see me as much as possible because we're still very honeymooney which is lovely. The past few weeks, he's been out with his friends every single night of the week, smoking more, drinking more, spending more money (even though spending money is a huge issue to him whenever it involves me) and I've never once told him that it makes me feel a bit pushed away because I don't want him to think I'm clingy. I asked him on the phone tonight to maybe invite me out for a drink once in a while, and he claimed he didn't know my schedule, even though I sent it to him a week ago. Hence why I'm asking this question here...

I've felt so lonely that his attention has gone from 100% to basically 50% and even though I see my friends too, he still means so much to me and I'm worried he's losing interest in me because it sounds like he's slipping through my fingers and doesn't want to see me as much. I adore him and wear my heart on my sleeve, tell him how much I love him as much as possible and his romantic side has just become non existent and mine has remained. I don't want to lose him, I just don't know what to do. He tells me he loves me and I believe him but I'm just hurt and feeling alone right now.