Stranded in the Old West, Doc (Christopher Lloyd) meets and falls in love with Clara (Mary Steenburgen).
While not a direct lift, it’s similar to the conundrum that Dr. Emmet Brown faced in the concluding chapter of the Back to the Future trilogy.
This one is a little more obtuse than the others.
So when Marty (Michael J. Fox arrives to “rescue” Doc, he has to make a very tough decision of whether he should stay in this world, where he’s happy, even if he knows he’ll be shot to death.