The finale saw Wesley's character Stefan let Elena (Nina Dobrev) drown - and consequently turn into a vampire - after she asked him to save her friend Matt (Zach Roerig) instead.
However, Wesley has now told Digital Spy that he believes Stefan would have ignored Elena's requests in order to save her life.
Watch Paul Wesley speaking to Digital Spy about the end of season three of The Vampire Diaries below:
Wesley explained that he was "confused" by the idea of the scene at first, but revealed that the writers had justified it by saying Stefan was "physically" unable to save Elena and was also learning to let her make her own choices.
"I don't buy it," he admitted. "I'll be completely honest. The writers are probably going to get mad at me! I don't buy it, but it is what it is and so we have to live with it.
"I personally think Stefan would have just went, 'I don't really care what the hell you have to say', and would have grabbed her - but it is a story and frustrating things happen in life and stories."
Wesley also revealed that he expects Stefan to "have a lot of guilt" and "blame himself" for Elena's transition, adding that her change into a vampire will make her "reassess" everything.
"I don't think it's going to be like, 'I'm picking Stefan and we're going to be happy now'," he said. "It's going to be a completely different show now, I think."
The Vampire Diaries season three is available from Monday (August 20) in the UK.