At least one quick kiss to show they were in love. They really only bicker throughout the whole movie. There's never any warmhearted moments. Sure there was one scene where Cheryl stroked his arm in the car but that's about it.
Frankly, I found it extremely believable that there wasn't, I can certainly see why each would fall out of love with the other. I mean she's supporting the family and running the house and bossing everyone around, and doesn't seem to have a lot of energy left for romance or sex. And he's an unemployed dickweed who's wasting his life on this bullshit philosophy that will never sell, and leaving his wife to support the family and run the house and have no energy left for anything fun.
Frankly, they treated each other better than a lot of people would, under those circumstances.
The fact that they're still together and not constantly fighting, or that she's not screaming at him to get a job or get out the way I would, does imply that there is still love there. But yeah, there seem to be some fairly serious issues in the marriage, that aren't resolved during the course of the movie.