Is it over?

Me and my boyfriend have been together for a year and a half off and on. We have a little nine month old baby, also. Everytime we have sex, it's hot and passionate. But lately, we both just seem bored. We both go down on each other and we switch up positions, but he hasn't "finished" in about a week and a half and it's hard for him to get real hard. Right now, it seems like we have sex because we think that's what the other wants and expects. What can I do to help us get out of this rut? Should I ask him why he isn't finishing?