A lot of women do this, obviously. The reason they do it is because they can get something out of you, either a good performance rating or free helps and advices. In your case, the junior also knows very well that you're not really a potential boyfriend material for her, probably because ahe didn't find you attractive enough or too old. Women in their 20s usually aren’t going to date someone in their 40s, unless you're really well-off (being a senior is not usually enough). My advice: cut ties with her unless you're okay with being used by her. Either way, you both get something out of each other.