'Fixer Upper' Stars Chip & Joanna Gaines' 'Marriage Is Falling Apart!'

Fixer Upper couple Chip and Joanna Gaines are putting on a happy face following the birth of their fifth baby — but the little bundle of joy may be the wrecking ball that demolishes their marriage.

Insiders told RadarOnline.com that the weight of raising five kids, the demands of their massive empire, plus allegations that their construction work is substandard — and possibly even criminal — have put an insurmountable strain on the pair's relationship.

Chip and Joanna, who have been married 15 years, welcomed their new son, Crew, June 21. Since then, a source said, "They have been stretched to the limit, and people close to them say this may be the final straw that breaks the back of their relationship."

The pregnancy came just weeks after last September's announcement that the fifth season of their home renovation show Fixer Upper would be the last.

But insiders claimed the time off hasn't been enough to ease the mounting pressures on the reality couple.

"Frankly, Chip and Jo don't think they can hide their problems anymore," a source said. "They've been pushed to exhaustion. Now with a baby on board, you can forget about intimacy!"

Their extensive brand — which includes merchandise collections, a bed-and-breakfast, books and the quarterly magazine Magnolia Journal — took a massive hit in February when a former business partner said Chip is a corner-cutting cowboy who stiffed him for over $9,000. He also charged Chip failed to get proper construction permits, hired unlicensed contractors and did slipshod work.