If the marriage was solemnised in such a way that the girl was accorded a gothra before the marriage and subsequently her gothra got changed during the marriage, then there is no question of rights of the girl to perform such rituals of Brahmins. If the Girl in question did not have any such gothra, say from Christian/Muslim community and got married to Brahmin boy, and the girl still continues to eat prevented foods, then how come she can be allowed to perform ?
Just because the girls loves such rituals as Photo Ops. or the Boy just wishes that the couple be allowed/accomodatd into Brahmin community ? Or just because the Vadhyar is greedy ? or some varrattu gaoravam ?
During Rig Vedic period there was no caste or varna system existed. Also Varna System is not based on colour though we call it based on colour. The definition of Colour here means based on Tapo, Raja and Teja. Based on this colour terminology during Rig Vedic period itself due to behavioral model of Varna system evolved. It is also pertinent to mention here that because of a particular person who committed grievous sins were excluded from a particular Varna as outcastes (untouchables) and considered outside the Varna system.
01. The Brahmin class is modeled in the epic, as the archetype default state of man dedicated to truth, austerity and pure conduct.
02. Those who were inclined to anger, pleasures and boldness attained the Kshtriya Varna;
03. Those who were inclined to cattle rearing and living off the plough attained the Vaishyas;
04. Those who were fond of violence, covetousness and impurity attained the Shudras.
In India during Indus Vally Civilisation period Pancha Dravidians were existed in Saraswati River Delta. Aryan originated from Europe invated India and occupied Saraswathi River Delta pushing the Pancha Dravidians to Southern Parts of India. The Aryans who conquered Dravidians spread out to North India and adopted Hinduism from Dravidians. It is Aryans who classified the caste system in India which prevails even today. North Indians though adopted Hinduism but their Sutras or Smrithis are of different from Pancha Dravidians.
As per Hindu Dharma each Varna has its own lineage system and Gothras whether it is Aryans or Dravidians. Gothra System followed by all irrespective of Aryan or Dravidian is based on paternalinage (means Father Lineage).
As far as marriages are concerned as per Indian system of marriage is based on vertical system not like horizontal system of marriage being followed in western countries. Vertical System of marriages are based on paternalinage not maternalinage. As per Puranas a man should marry the same varna woman but no matter with higher caste. (Here higher caste means within the same varna but sub-caste but lower sub-cast should be avoided, as far as possible). It is scientifically proved marriages prohibited in the same Gothra due to blood relationship. Same Gothra people are considered as brothers and sisters. Women receives importance in family circle once she gets married and once the girl’s father performed Panigrahanam the responsibility of father ceased and the entire responsibility lies on the shoulders of husband reason being the girl automatically adopts husbands gothram relinquishing her entire birth place relationships and bondage. Mangalya Dharanam is not considered as marriage ceremony in our custom. Panigrahanam is considered as Marriage.
Based on this lineage system and Gothras 40 samaskarams are being performed by all of us irrespective of Varna category.
As per lineage and Gothra system one of the samaskaram being performed is Shrarda in which Sapinda being performed after this ritual ceremony the deceased soul reaches either swarga or naraka according to Karma. The person who performs ritual ceremony for his ancesters carry in his body his father’s and ancesters Sapinda Particles with the Gothra of his father and ancesters. Also it is mentioned in Ramayana when Lord Sri Ram performed Ashwamedha Yagam and ancesteral ceremonies Goddess Sita was exiled and not available besides him and as per Hindu Dharma performing rituals without spouse is not permissible and not beneficial. The Sage Vashista confirms (Though Sri Ram was shatriya) that though Sita is alive and exiled to support Sri Ram to uplift his Raj Dharma her Golden Idol (Not any other kind of idol) can be placed nearby you while performing the rituals. Therefore, it is mandatory for performing every samaskarkam spouse presence is very much essential and without spouse even if Kartha performs his rites. For performing ancesteral rites one has to utter the lineage gothram. In case of inter caste or love marriage either belongs to lower varna of the boy or same gothra. Under this circumstances, spouse can’t participate in the rituals like Mangali Pondugal or Shrardam or Namakaranam, Srimantham, Nandi Srardam, etc. etc. There is no system in our Hindu Dharma to adopt and become Hindu from other caste. Even in Hindu Dharma prohibits varna to varna conversion. The person marries other caste girl will be excommunicated automatically from Hindu Society once become Grahasta a person. Such person can very well perform his rituals for his own satisfaction and it will not fetch ultimate result which Hindu Dharma believes in every action.
Similarly, in our Hindu Dharma Divorce is not permitted under no circumstances which are common in western culture.