I think there are some rather harsh opinions expressed above, as some try to empathise with one of the involved individuals only. Both parties have feelings and emotions, and the situation was fraught. The guy in particular feeling in need of comfort after an emotional break up. Ciaraciara allowed her repressed feelings to come to the fore. I don't think one should judge harshly any of those involved, even though in hindsight all could have acted more wisely, were they capable of analysing the situation with a 'level head'.
The reality is that if one has been involved in a partnership for some time, it will take time to accept it has ended. Until then there may be many attempts to heal the problems and get back together again. Having attempted to rush that "mourning" period you have found there are risks involved.
Even if someone who have had long term feeling for does experience problems with their existing relationship, you need to ignore it. At the very least until they are truly accepting of the change in circumstances and they are thinking straight again.
But IMO if someone hasn't jumped at the chance of a relationship with you earlier, then you are probably wasting your opportunities, holding on to the possibility that something might happen in the future. Look out for someone free to appreciate you intimately now and don't compare with fantasies about how much better it would be with someone who's unavailable. A bird in the hand is worth two in the bush; and building a real relationship with someone may have difficulties living up to an ideal fantasy one.