Theres a lot of speculation going on in here. I'll throw another spanner into the works. What if the reason they broke up a week before Lawson went into the house, was that his girlfriend had slept with someone else? Then after having time to analyse it more, when he has more time to think about it in the house, Lawson has said stuff it. He obviously has feelings for Cat, stronger than the ones for his girlfriend or ex.
Living in a confined space when half of them are certifiable, I would be happy to just find someone I could have a sensible conversation with. Just because we dont like whats implied or has happened, doesnt mean that the teens/tweens wont understand it. They are the main ones that vote and surely a house romance on a higher level than Traisha, might be welcomed. Its not always the nicest or kindest person that wins Big Brother, its usually the one that engages with the general audience, the best. Plus its in Big Brothers interests to keep them both in longer, if the ratings happen to increase.