How can I tell if my boyfriend is serious about our relationship?

We're both 24 and we've been dating for about a year. There was no regular courtship and he's never said "I love you." But he's been honest to me (most of the time) and loyal. He's never introduced me to his parents but I believe they already know about me. He's very secretive and traditional. He'd used to say "Its for me to know and for them to find out" when people would ask about us. He's been supportive when I had major problems. He's very sweet when we're alone but he doesn't like it when I tend to show PDA (public display of affection). He's never asked if I love him, rather he said he wanted me to TRUST him. I tried to be cool about this whole READ the ACTIONS thing but I can't help but wonder if the guy really does love me or not. His actions tells me that he does but there was no confirmation of his feelings through words.