In this day and age, with easy and discreet modes of communication, it can become dangerous for a person with (a) previous flame/s to fall into some kind of fitnah if a strong conscious effort is not made to avoid it.
For example, let's say a girl knows a guy and they plan to marry but it doesn't work out. The girl ends up marrying someone else a while later and all seems to be going smoothly for a couple of months or maybe a year or two.
Then suddenly the husband starts to 'change' and becomes neglectful of her and she doesn't feel so loved. Suppose she in that depressed state, receives an email or text or call out of the blue from her former flame asking how she was etc. It's possible that under such a circumstance, she could be tempted to converse with him more and more and soon enough, find that she enjoys this new found attention and rekindling of old feelings. It might not even get into proper zina but there is a huge possibility of an 'emotional affair' taking place.
Or imagine the case where it is the guy who has known someone and she one day sends him some message saying how her current husband is abusive and she's unhappy in her marriage and has nobody to turn to but him. Again, same kind of thing could happen as above.
Care really needs to be taken and vigilance maintained. Not just in the initial years of marriage but throughout.
