In ancient times it is common that the marriage age is very low & due to non availability of effective medicines the term of human life is also low.

In invitations mentioning the name of god is our religious practice.

Not convincing , not satisfied!!

I can try to answer you! Shri Ram and Sita Vibhogame is sung because of the characters(Only) Sita mata and Shri Ram Both of them never stepped out of there maryadas()as the ideal couple.Shri Ram was known as Purshottam Ram and devi sita is known as vedhi,sati etc and was considered as most pios.Now here we understand that they had lot of materialistic trouble but singing the hymn on there name is to get there blessings that the couple will be as tolerable,Honest and dedicated as ram and sita(as we know every person in world faces troubles and up and down)
Ram and Sita could not live long but they have set an example of unconditional love to each other,inspite of so many up and downs to teach humanity that no matter how this materialistic society or troubles treats you,one should never give up traits of ideal husband or wife.

for example Some time , Rama decided to perform the horse sacrifice (ashvamedha yagya) which is the highest ritual a king can strive to. There was a technical snag however. Of the hundreds of ceremonies a Hindu has to perform, not one can be performed without a wife. Therefore many in Rama's retinue suggested that he remarry. A suggestion he firmly rejected: "In the heart of Rama there is place for only one woman and that one is Sita."and for sitaji it was just one man we all know ...no need for i examples i assume.

Here Idea of singing that hymn is not that xyz couple will get same problems but ....to get blessings of them so that they gain same qualities and shine.

This question is a good question.I would like to add that in north india people still dont say much as " ram sita jodi "instead they say shiv parvati jodi or radha krishna jodi as most of them think as you do,as everyone has a different angle to look at things.However saying sita ram jodi is also no issues if u commenting on there dedication to each other.

Ram in Sanscrit means Dark Blue/ Black which is Universe.
Sita/ Janavi means Earth. The vibration created from all the Planets activates the Earth, and all living beings including Plants, Animals etc., it also fertilizes the earth so that Earth also is activated. With out other Planets there is no Earth and its activities. These vibrations created by the universe penetrates in to the human body at the time of birth when the lungs actvated and the power of the planets seeds in the human body and our fate is fixed on that. Jagath= the universe, Aham = inside the body means Jathagam (Horoscope) Co- Operation from the
Hola= Time/ period of time/Hora-sastra=the first of the four Yugas or ages (i. e. the
best or golden age as the age of general virtue and
purity, comprising 1,728,000 years of men; hard, f. (borrowed fr. Gr. &pa), the
rising of a zodiacal sign ; part of the duration of a
sign ; an hour ; a mark, line ; a particular scientific
work or science, (probably astrological)
Based on this Horoscope is written.

So the Rama is none other than the universe that containes the Planets and their activations and Janavi is none other the Earth.
So some Hindus when writting there letter at the beginning put Rama Jayam, meaning The Universe will win!
The Universe is Identified as AhuraMazda in B.C 10000,
and as Rama in B.C.8000 and as Krishna in B.C 4500.
As Christ in B.C 1 and as Allah in A.D.632.

Mate,

I am not sure if the age mentioned there is correct or not.
As far as I read Valmiki Ramayana, Rama was 16 years when Viswamithra requested Rama's assitance.

Sita and Rama's Wedding happened in Videha Kingdone itself (Janaka's Kingdom). It is also not true that the Dasaradha and his family are not present for wedding.

You should be aware the fact that Swayamvara and Wedding are different. Hence Wedding is held as per Tradition and is described beautifully.

In Valmiki Ramayana, it is also mentioned that after marriage when Dasaradha is returning to Ayodhya with Rama- Sita, Lakshmana - Urmila, Bharatha - Mandavi, Sathrughna -Srathukeerthi, Parasurama came on the way and challenged Rama to also bend Vishnu Dhanussu (Bow).

After Rama went for exile for 14 years, Bharatha came to him to
1. Return kingdom to Rama
2. Dasaradha's death and to make him perform required Karmas.
3. Convery his sincere Apologies.

However, Since Rama is strict in his principles,he denied the Kingdom. It is then Bharatha took Rama's wooden footwear to place them on the throne and rule the Kingdom on Rama's behalf.

You also do not have any Television etc at that time.
When you mean Aranyavasa for14 years, you mean it.
It is not like... we roam around parks etc.

Site- Rama, Lakshamana had moved across different places and finally settled in Panchavati. Hence the news that Sita was kidnapped never reached Ayodhya until Rama has returned.

Moreover, the destruction of Ravana is destined in hands of Rama and Vanaras. Remember the boon of Raavana where he can not be killed by Gods, Gandharvas, Kinneras, Kimpurushas, Asuras. Hence few gods took birth as Vaanaras to assist Rama.

Hanuman himself is said to be the fire that is caused in Siva's throat when he swallowed the Kaalakoota Poison.
When Maha Vishnu became Jaganmohini to cool Siva, this fire has come to Earth where it is taken care until Thretha Yuga which is then carried by God of Air (Pavana Deva).

Coming to sending away Sita:
In thretha Yuga, the duties of a King are very strict.
A King's main aim to
1. Rule the kingdom in the best interest of Dharma.
2. Lead by Example to whole Kingdom (Yatha Raaja, tathaa praja).
3. Kings personal life, wife, brothers comes only after people and Dharma.

After returning from Lanka, the story is not aware to most of the citizens as there is no "MEDIA" at that time.
All people know is Sita was kidnapped by Raavana, a well known Ausra in whole world for almost 6 months. Hence they doubted her. As a King, when he can not prove the serenity, Sacredity of Sita, he has to banish her.

Then Sita gave birth to two kids - Lava and Kusa. These kids are brought up in Maharshi Valmiki's Ashram. These kids have taken the duty of spreading Ramayan (story so far) among the citizens. however, they are not aware that they themselves are Rama's kids and their mother is Sita.
At the end, when Rama requested Sita to come back to Kingdom, Sita refused to come back. The reason being, people at that time cared very less about their life. Dharma, Satya, Vratha, Word (promise) are only important in life. She doesnot want to be the queen of same kingdom from where she is banished. The reason is, then the King would be proved wrong. This would be a black mark on him. As a wife, she cannot have the thought, hence she requested her mother (Mother Earth) to take her near.

Hope i made it clean enough :) :)