This sounds SO much like my narcissistic fuckwit ex. Was attentive, paid compliments, lovebombed when we were together...but would find reasons I couldn’t go out with his friends/turned his phone off on nights we were apart/sent photos afterwards (to prove he was where he said he was), I only saw him on his terms and it was usually only once a week. Made me think I was crazy, demanding, high maintenance, not understanding the incredible demands on his time, etc etc. I stayed with him for way too long because, like you, I was “in love”, I thought. I believed the fact that I was miserable was my problem, and I needed to be more compassionate to him 
I eventually got the strength to end it - waited until there was ‘cause and effect’ in evidence (as a PP mentioned; this stops them playing the pity card or gaslighting you into thinking you’re a bitch!) I stuck with him for ages longer than I should have, despite having vague suspicions, despite being unhappy, because I felt like I’d be being a bitch if I left him (and I wondered if I really was just crazy)!
A couple of months later I had a message out of the blue from one of his female friends (who I’d never been allowed to meet), because she thought I’d maybe been seeing him at some point and she was concerned about her friend who’d been in a relationship with him for about a year. That message sparked a lot of messages between lots of women, phone calls, meeting up...because he’d literally been stringing multiple women along and none of us had the faintest idea. It turned out I wasn’t crazy and paranoid after all. Found out he was binning me off to go to parties and lying about it, and he was using photos taken by all of us to send to each other as ‘proof’ of what he was doing, so none of us suspected. He would send messages to us while lying in bed next to another woman, just to give a little drop of affection and make sure we were all kept on the hook. Several of us had been in apparently long term, committed relationships with him at the same time.
I’m not saying this is what’s happening here, and there’s every chance he’s seeing only you and just being a dickhead. I am saying that your boyfriend’s behaviour sounds familiar and even if he doesn’t have someone else, he definitely isn’t making you happy, he’s not making you a priority, it doesn’t sound like you’re getting what you’d like from a relationship, you can do better! Get rid, and don’t doubt your decision! You are worth way more than this. Stay strong, and don’t let him reel you back in once you’ve done it.
(Sorry, this was a super long post 
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