I have done broad research on denial of marriage in astrology and found out some key combinations to check the denial or no marriage yoga in any chart. These combinations must be seen in D1 and further D9 and D60 must give the confirmation.

Here are the key yogas:

Ketu is a separative and a saintly planet (who doesnt want to acquire relationship desires) and when it combines with venus or close to ascendant or 7th house cusp with 5 degrees, it is the first indication of denial of marriage in a chart.
If ketu is present in ascendant of D1 and D9 chart both with venus in affliction, then it clearly means the person would live a single life forever and will never marry
If the nakshatra lord and sub lord of 7th house cusp is no way connected with 2,7 or 11 house then there is no marriage yoga in person’s chart
If 7th lord goes in 12th house of isolation with ketu then the chances of no marriage is more
If 7th lord is aspected by many malefics like ketu and saturn, the chances of marriage is less
In some rare texts, ascetism or sanyas yoga is given which are given below:

Very strong Moon and lagna/lagna lord with no house being majorly afflicted
Presence of four or more planets (none being combust) in the same house
A strong mahapurush yoga or a mahabhagya yoga along with any indications of sanyas
Venus being aspected by Saturn alone, being debilitated in Navamsa but strong in all other divisions.
Venus conjoined moon with malefics likes saturn & mars in the 8th house makes a great sanyasi yoga