If you are looking for a younger woman to date try and keep the age difference between you to no more than 13 years for Bulgarian ladies and 16 years for Russian ladies.
The reason for the slight difference in dating is the imbalance in the population in Russia; due to sheer lack of men it is simply harder to find a husband for Russian brides or Russian women.
If they are grown, it may strike them as practically incestuous to learn that Mom or Dad is dating someone their same age.
They may worry about fortune hunters or a compromised inheritance, or struggle to perceive their new 40-year-old stepmother in a maternal light.
In some cases in Russia one can find a woman much younger partner for dating but remember, the greater your age difference, the less the chances of your marriage surviving and more chances of getting married to someone who has no feelings for you, but plenty of financial plans...