How do I prove to him that i love him?

The man of my dreams has been in and out of my life for the last 2 years. I love him soo much and sometimes he says he likes me and sometimes he says he doesnt know and last week he said there was nothing between us. One night he got drunk and text me telling me he loved me and asked me to marry him, the next day he said he was drunk.He got hurt badly a few years back by a girl and is now very weary and doesnt trust anyone. We have slept together and he meets me alot and we kiss and talk. he is also in the harness racing game where its "cool" to sleep around etc. and i have heard that he always has a girl on the go....but when we are together the feeling and attraction and conversation and kisses are amazing. I think he is scared of commitment because he doesnt trust anyone. I need a big grand gesture to make him realise I am serious about him and love him and to make him believe me. Please help