To sneak around to get it on. Most fornication is done deceptively.
Things were tough in the early 1500s as you know, and women were simply property. Promises which are coerced with threat of violence are not valid ~ I suggest you learn to study that period ~ let's say from 1400 to 1600, with a very open mind. Did you know that Jeanne d'Arc had to be accompanied by loyal armed men day and night to protect her from being raped by her own troops? Even with her security guaranteed by the French royal family, men would attack her or any other woman away from her own male relatives just because they could, and most believed they were supposed to ~ else women would just run wild and ruin everything.
That sort of attitude didn't begin abating in much of Europe until the 1600s, but by then the abuse was pretty much limited to targeting 'witches' ~
Besides equating Luther's marriage to homosexual marriage, you have further absolved yourself as one who objectively deals with an issue.
You quoted wiki, and i will quote more, besides other sources.
It is certain that her father sent the five year old Katherina to the Benedictine cloister in Brehna in 1504 for education. This is documented in a letter from Laurentius Zoch to Martin Luther, written on October 30, 1531...At the age of nine she moved to the Cistercian monastery Marienthron (Mary's Throne) in Nimbschen, near Grimma, where her maternal aunt was already a member of the community. - http://en.wikipedia.org/wiki/Katharina_von_Bora#Marriage_to_Luther
Obstacle to the Free Egress of the Religious. The cloistered religious may not go outside their material cloister without permission...Canonical legislation carefully provides that religious, when not employed in the functions of the sacred ministry, shall reside in monasteries. The Council of Trent had already forbidden them to leave the monastery without permission under pretext of meeting their superiors. The bishop can and must punish the violators of this law of residence (Sess. XXIV, De Reg. et Mon., c. iv).
Those parts of the convent to which the nuns have access are all within the cloister, the choir not excepted. Here the law recognizes no neutral territory. If the convent church be public, the nuns cannot go into those parts accessible to the people. Further, the building should be so constructed that neither the sisters can look outside their enclosure, nor their neighbours see into the court-yards or gardens at the disposal of the sisters.
Obstacle to Egress. Under no pretext may the sisters go outside their cloister without a legitimate cause approved of by the bishop. Such is the legislation of the Council of Trent (Sess. XXV, De. Reg. et Mon. c.v.) St. Pius V. restricting still more this law, recognized only three legitimate causes: fire, leprosy, and contagious malady.
However, cloistered nuns are not absolutely forbidden all intercourse with the outside world. They may of course receive letters; they may also receive visitors in the convent parlour, provided that they they remain behind the grating, or grille, erected there. For such visits a reasonable cause and a permission from the bishop is usually needed .
The conditions for a visit by a male religious are very severe; according to some authors he can only receive permission if he is a blood relation to the first or second degree, and then only four times a year. Further, although an irregular visit on the part of a lay person or secular priest does not constitute a grave a fault, any visit without leave is a mortal sin for the religious. http://www.newadvent.org/cathen/04060a.htm
On Easter eve, 4 April 1523, Luther sent Leonhard Köppe, a city councilman of Torgau and merchant who regularly delivered herring to the monastery. The nuns successfully escaped by hiding in Köppe's covered wagon among the fish barrels, and fled to Wittenberg. [9]
Luther at first asked the parents and relations of the refugee nuns to admit them again into their houses, but they declined to receive them, possibly as this was participating in a crime under canon law.[10] Within two years, Luther was able to arrange homes, marriages, or employment for all of the escaped nuns—except for Katharina. She first was housed with the family of Philipp Reichenbach, the city clerk of Wittenberg, and later went to the home of Lucas Cranach the Elder and his wife, Barbara. - http://en.wikipedia.org/wiki/Katharina_von_Bora#Life_as_a_nun
Luther heard of the plight of twelve nuns who wanted to leave their convent but were prevented from doing so by their superiors. Although Luther realized that to aid them was a capital offense, he engaged the services of a merchant who periodically delivered barrels of herring to the convent. The merchant hid the nuns on his cart, making it appear that they were barrels being taken away.
After their escape, the nuns were presented to Luther. He tried to find them homes, husbands, or work, hoping that with time they all would marry. Eventually they all married except one: Katherine von Bora. When Luther met her two years later, she told him that she had not been able to find a husband. Luther decided to take her as his wife.- http://mluther.ccws.org/reformer/xi.html
After a year of marriage Luther wrote another friend, "My Katie is in all things so obliging and pleasing to me that I would not exchange my poverty for the riches of Croesus." Luther, the former celibate monk, now exalted marriage, exclaiming, "There is no bond on earth so sweet, nor any separation so bitter, as that which occurs in a good marriage." - http://www.blogher.com/frame.php?url=http://www.reformationtours.com/site/490868/page/204052