Rudolph's private letters make it clear that his marriage to Stephanie started out well enough, the couple were not in love but they were friendly Stephanie tried to share his interests and they both adored their little daughter. It is even possible that Rudolph's infidelity wasn't an issue as far as his wife was concerned until he gave her gonorrhea. After that relations deteriorated markedly and understandably!

On the other hand the Hapsburg habit of marrying cousins might have been politically wise but it was genetically disastrous.