I know that it is permissible for the fasting person to kiss his wife during the day in Ramadan, but what is the ruling if the man or his wife discovers that maniy was emitted as a result of that? Please note that that may be due to the fact that they got married one week before the beginning of the month of Ramadan.

Praise be to Allah

Firstly: 

Yes, it is permissible for a person who is fasting to kiss his wife during
the day in Ramadan, and for them to enjoy physical intimacy so long as it
will not lead to intercourse or emission of maniy. 

It
was narrated that ‘Aa’ishah (may Allah be pleased with her) said:
The Messenger of Allah (blessings
and peace of Allah be upon him) used to kiss and touch (his wife) when he
was fasting, but he was the most able of you to control his desire. 

Narrated by al-Bukhaari (1927) and Muslim (1106) 

What is meant by the words “but he was the most able of you to control his
desire” is that he (blessings and peace of Allah be upon him) was able to
control himself and to control his desire, so he would enjoy intimacy but
that would not lead to intercourse or emission of maniy. 

But if a man is afraid that if he kisses his wife whilst he is fasting, or
enjoys intimacy with her, that this will lead to intercourse or emission of
maniy, then he should refrain from that intimacy, so that he will not
invalidate his fast. 

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: Kissing, with
regard to one who is fasting, is divided into two categories: that which is
permissible and that which is prohibited. 

That which is prohibited is if he cannot be sure that he will not render his
fast invalid. 

That which is permissible is of two types:

1.    
where kissing will
not provoke desire at all

2.    
where kissing may
provoke desire, but he is confident that his fast will not be rendered
invalid. 

As
for actions other than kissing that may lead to intercourse, such as
embracing and the like, they come under the same ruling as kissing and there
is no differentiation.

End quote from ash-Sharh al-Mumti‘ (6/429) 

Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allah have mercy on him) was asked: If a
man kisses his wife during the day in Ramadan, or touches her, does that
invalidate his fast or not? 

He
replied:

If
a man kisses his wife, touches her and is intimate with her, without having
intercourse, whilst he is fasting, all of that is permissible and there is
nothing wrong with it, because the Prophet (blessings and peace of Allah be
upon him) used to kiss his wife whilst he was fasting, and he used to touch
her whilst he was fasting. But if he fears that he may end up doing that
which Allah has prohibited to him, because he is easily aroused, then it is
makrooh for him to do that. If he ejaculates, then he must refrain from
eating and so on for the rest of the day, and he must make up that day’s
fast, but he does not have to offer expiation, according to the majority of
scholars.

End quote from Fataawa ash-Shaykh Ibn Baaz (15/315) 

Secondly: 

If
a man kisses his wife whilst he is fasting and emits maniy, then he has
invalidated his fast and he has to make up that day’s fast after Ramadan
ends. 

Ibn Qudaamah (may Allah have mercy on him) said: If the fasting person
kisses his wife and ejaculates, then he has broken his fast, and there is no
difference of scholarly opinion concerning that, as far as we know.

End quote from al-Mughni (4/361) 

But he does not have to offer expiation, because expiation is only required
if he breaks his fast by having intercourse. Please see fatwa no.
49750. 

And Allah knows best.