Egon was in the middle of working out Einstein's theory of mass-energy equivalence (Energy equals mass times the speed of light squared). Janine happens to come in and see what he is working on. Seems that Egon is slowly accepting her affection and gets...sidetracked, which is a great thing!
Janine at one point in the series mentioned how it was his mind that she originally fell in love with. Hey who wouldn't want to love a super smart scientist?

Drawn by  lilifox