Well, they will only mate if thwy are:
5 years old
and they love each other 4 hearts. (♥♥♥♥)
WHenever you do present connection after that they will kiss.
If you keep connecting using present, one of them (Or both) will shake thier head, saying No. Fireworks will go off. The female will then have the babys and one will go to the male ;3