As Ketu signifies detachment and renunciation, due to it’s mysterious properties it may create delay in marriage or even can deny both.
Ketu is headless and best shows results in the spirituality, sadhna, Tyag, and Sanyasi life. 7th house holds an importance for marriage and marriage related prospects.
Happiness and all issues related to marriage are seen from the 7th house, similarly the strong 7th house denotes happiness and success and happiness in marriage and married life.
Planets like Saturn, Mars, Rahu and Ketu if occupies the 7th house, then delay and other problems related to marriage and married life are sure. On the other hand Ketu Ketu in the 7th house results in many problems like as follows;
Delay in marriage
Skipping of marriage proposals
Ego clashes with spouse
Difference in opinion
No match in the mental wavelength between couples
So all above problems are indicated with the Ketu in the 7th house. As per my practical experience Ketu in the 7th house results problems in two ways if somehow your married life will sustain by any manner then health of the spouse may get affected, it means Ketu spoil the sukh of married life. Because the malefic influence of Ketu is not suitable in the 7th house, since 7th house is not a good seat for the Ketu and it spoils the happiness by affecting the married life.
I hope this answers your concern, feel free to post comment.