Post-sex vaginal tear with light bleeding. could his penis be too wide?

See your gyn: I have seen this possibility a number of times. However, post-coital bleeding should be evaluated by your gyn. Depending on your menopausal status and the source of the bleeding, this may have different medical implications.

Penis: Post coital bleeding may be significant, but if occurs only once, probably secondary to trauma. Use lots of lubrication. Unlikely it's too wide.