Hi Pixie...

Do yourself and your boyfriend a HUGE favor. Stop thinking about his "problem". Stop making it a BIG "problem".

Do right to yourself - if you are comfortable saying "I love you " to him - say it - whenever you want to, as often as you want to. Don't worry about whether it will make him feel "pressured". If he squacks, tell hiom you have as much right to express your feelings as he does to insist on expressing that he just "likes" you. If he acuses you of just doing it to "pressure" him tell him, "No, I'm doing it because it's what I feel and I am NOT going to stop saying it because of YOUR attitude. If I stop saying it, it will be because I have stopped loving you.",. and THAT, Ferris Bueler, is how it IS."
From now on when he pulls some trite refusal - realize it is him trying to jerk your chain. It hasn't anything to do with some deeps serious hurt he's had. It's nothing more than him pushing a "hot button" he's found in you. He looks for your discomfort/disappointment/embarrassment to remind him he has power over you because you have feelings for him.
Not telling you he loves you is one thing. Doing it in a context to cause you embarrassment is another.

The issue you have the right to assert yourself and demand respect from is his doing it to humiliate you.

I'd bet his little remarks come out most when the two of you are around others, which is what makes me think he feels the need to assert his "power" over you. Bottom line - he's an emotional bully. Good news is, bullies fold once you stand up to their apple sauce.

When he does it, stay calm, put your "Dirty Harry face" on and halt HIM in front of everyone and say - "look Ferris. If you can't say "I love you" from your heart in private that's your way and you know I don't bug you about it. But intentionally making it an issue in front of people just to to humiliate me IS "across the line" and you owe me an apology for that."
Sound and look like you are serious and then be quiet making it clear you are waiting for the apology. If he comes back with some smartypants remark or a denial - don't change your appearance at all and don't respond... just make it clear you are still waiting for that apology. He started it - and this time he has only one way to finish it.
If he starts trying to pass it all off as "funny" just keep looking at him and repeat "I want the apology, Ferris." If you don't get it, don't get mad, just distance yourself from him for the evening or the night or a couple days and don't let him "make it all better" until he say's "I'm sorry". You'll see, having no choice but to say I'm sorry" will make saying "I love you" look pretty good to him.

But you have to remember not to argue with him about whether he was trying to humiliate you. He IS Guilty. There IS NO argument, no fight, no debate, no discussion, no "I was just kiddin'", no "Gimme sympathy", no laughing apology.
There is a sincere apology or there is distance/silence - those are his only two choices. They will be his only two choices tonight, tomorrow, the next day and next week. You are drawing that line in indelible ink. It's the ony way to handle bullies. As long as they can keep you talking, they are winning because they don't have to apologize and admit they are wrong. - and that is their only license to keep bullying you. Take it away from him.

Good Luck !

P.S. Will add that now is a perfect opportunity for you to learn how to recognize a bully and how to stand up to them and take the wind out of their sails. Getting rid of this one so you can go get bullied by the next guy just leaves you with a "new guy - same problem" situation. Stand up for yourself now.