I'm guessing while you guys were apart he got dependent on satisfying his only sexual needs with masturbation and porn. Now he has you, but he finds the ease , no fuss no muss, no performance anxiety easy biz of masturbation to porn is still a reliable outlet for his releases. This has nothing to do with you or how much he's into you, this is selfishness, lazyness and habit.
You have to talk to him about how you feel... how you want to feel wanted by him, how you want to be the one that pleases him when he has sexual energy. If he is masturbating in the morning when he gets up, then you start groping him at 2pm... he will not be in the mood because his needs are met already by himself... he probably doesn't realize how important him having sex with you is to you, not just for your own sexual desires but to feel wanted and close to him.
You should just have an open talk with him about his sexual needs, how often he feels the need to have an orgasm (not sex... because some guys don't associate their masturbation habits with sex.. they think... oh i only need sex once a week, while needing to masturbate once a day. They don't realize that if they didnt masturbate every day they'd want sex more than once a week). So talk to him about how often he needs to have an orgasm, talk to him about whether or not he feels bored or uncomfortable during your sex, if there are things he would like you to try... etc.
Find out if you guys are just on different schedules... maybe he's horniest in the mornings when you arent... then he masturbates, then your horny later and he's not... because hes drained of his energy... try to see if you guys just have your clocks crooked and see if you can adjust them so that you can meet in the middle.
I know how much this hurts your feelings... I've been down this road before. Don't let it make you feel undesirable, you aren't... you just need to talk to him about this, if he cares about you ... he's going to want to make you feel better... he's going to want to work with you on this. If he doesn't... then you know where you stand with him.
Let him know sex doesn't always have to be some passionate 2 hour session, that you'd be fine with occasional heated quickies... or pleasing him in other ways (if you are fine with that) when he is too tired to perform etc...
Let him know how happy it would make you to be the one making him feel good... maybe he doesn't even realize.