If she is neglected by her husband, a man showing attention and obvious attraction will make her feel good about herself, and makes her feel that she's worth something after all. She probably wants an affair, at least I don't see her wanting anything long-term. But a side-dish, and especially when it comes from a younger guy, it's boosting her ego and making her realise that she's still attractive. If you want 'to be used', as Inge put it, go for it, but I wouldn't have high expectations of it being anything long-term.