You don't "need" to climax in your girlfriend's mouth, actually. I was with a guy for quite a while who wasn't interested in anything beyond plain vanilla missionary and only 2-3 times per month at most. My libido was much higher and wilder than his, like by far, but I substituted with toys and porn on the in-between and then enjoyed our intimacy when he was up for it. I think he had serious depression issues that he refused to acknowledge or address. I was with another guy who would not let me mess with his nipples even though that's a huge turn-on for me. He just did not like it. I respected it, certain physical acts are not "needs" and if you're in love, you don't need your partner to fulfill your every erotic fantasy. Some things are shared and some things are fantasy for you on your own time while masturbating. This is the most natural and obvious thing when you're actually in love with someone.

So let's get real. You're not in love. You're 'comfortable'. And it's starting to turn you into a nasty person, the sort who feels entitled and so on. This is what happens when you stay in a relationship for all the wrong reasons. It slowly corrupts you like a poison, hurts your partner, and in the end the relationship collapses, anyway. Suck it up and be honest, have a graceful parting and let her move on to someone who will satisfy her, and allow yourself to do the same.