Saturday. (Beginning perhaps amended.) I know it is madness to keep this journal but it gives me a strange thrill to do so; and only a loving wife could decipher my microscopic script. Let me state with a sob that today my L. was sun-bathing on the so-called “piazza,” but her mother and some other woman were around all the time. Of course, I might have sat there in the rocker and pretended to read. Playing safe, I kept away, for I was afraid that the horrible, insane, ridiculous and pitiful tremor that palsied me might prevent me from making my entre with any semblance of casualness.
(Lolita, Vladimir Nabokov)
The event time of ‘might prevent’ exists since the time of ‘kept away,’ and so ‘might have prevented’ would not be possible, I think. But, when we shift the reference time of ‘might prevent’ from the past to speech time (the present), we could say ‘may prevent’ instead of ‘might prevent,’ without breaking semantic order. (Of course, though ‘might prevent’ is able to denote present tense, I’m asking for the use of ‘may.) Is it possible or is there some problem?