Marriage after a haraam relationship in which there was no zina

Firstly: 

A relationship between a man and a woman
outside of marriage, which is what is called an unlawful
relationship, is haraam, regardless of the level of this
relationship and whether it goes as far as an intimate
relationship or zina (sexual relationship), which is the most
reprehensible and abhorrent type of sins and one of the
gravest of major sins that poses the greatest danger to the
individual’s religious commitment and faith, or it is less
than that, such as looking, touching or kissing. All of that
is haraam and these are types of zina in the general sense,
and are things that lead to the greater immoral
action. 

See the answers to questions no. 27259,
23349 and 9465. 

Secondly: 

If marriage takes place after a haraam
relationship between a man and woman, then one of the
following scenarios must apply: 

1.

Either that marriage comes after an
illegitimate sexual relationship, in which case the marriage
is not valid except on the condition that both the man and
woman repent from zina and it be established that the woman
is not pregnant as a result of the haraam relationship,
because Allah, may He be exalted, says (interpretation of the
meaning): “The adulterer/fornicator marries not but an
adulteress/fornicatress or a Mushrikah; and the
adulteress/fornicatress, none marries her except an
adulterer/fornicater or a Mushrik [and that means that the
man who agrees to marry (have a sexual relation with) a
Mushrikah (female polytheist, pagan or idolatress) or a
prostitute, then surely, he is either an
adulterer/fornicator, or a Mushrik (polytheist, pagan or
idolater). And the woman who agrees to marry (have a sexual
relation with) a Mushrik (polytheist, pagan or idolater) or
an adulterer/fornicator, then she is either a prostitute or a
Mushrikah (female polytheist, pagan, or idolatress)]. Such a
thing is forbidden to the believers (of Islâmic Monotheism)”
[al-Noor 24:3]. 

For more information please see the answer
to questions no. 85335
and 11195. 

2.

That marriage comes after a haraam
relationship, but the relationship did not go as far as zina,
such as kissing, touching and other haraam actions that are
less serious than zina. In this case the marriage is valid,
because it cannot be said of those who fell into this haraam
relationship that they committed zina. 

For more information please see the answer
to question no. 106288. 

And Allah knows
best.