Why is he behaving like this?

i kw this guy for 3 yrs. we got on well n often travelled together. he asked me out most of the time. we never dated but sometimes we hv some level of intimacy like kissing n fonding etc. i told him i m not for fun n wanted a serious relationship n so we kept eachother as platonic friends. recently we started to get close again as i had more time n he doesnt hv much friends. i asked him if he likes me, he said he dont know. everytime we take a step closer, i can feel he trys to keep back off alittle. lately i told him i m gg for a date n he started questioning me about it. not that i am crazy about this guy but i am curious about his behaviour. i find that he always want me to spend time with him when he is free but he doesnt do the same for me. we hv been like this for about 2 yrs n i gave up wanting anything serious with him..