Colin Firth and wife Livia Giuggioli’s marriage is solid despite last week’s revelation that Giuggioli had a romance with another man during a recent separation, sources tell People.

“These two have a solid commitment, are on the same level, and worked through it,” says a source. “They got back together, and things are fine. They have a good marriage.”

“It’s not uncommon for a marriage to go through periods where it seems stale, especially with children involved,” adds the source.

The couple, who wed in 1997, have two sons, 16-year-old Luca and 15-year-old Matteo.

They “have a committed relationship,...