Luann de Lesseps and Tom D'Agostino are divorcing after seven months together

Luann de Lesseps is opening up about her decision to divorce Tom D’Agostino after seven months of marriage.

The Real Housewives of New York star reveals a major issue in their relationship in this week’s issue of PEOPLE: “Getting caught in the press going out and meeting with ex-girlfriends, that caused a lot of fights to go on,” she says.

De Lesseps, 52, recalls coming home from a dinner party, only for D’Agostino to head back out to meet a former flame.

“He ended up calling an ex-girlfriend to see where they were,” she explains. “And that’s when I said to myself, ‘This is the last straw. This is really the last straw.'”

De Lesseps credits the Bravo reality show for helping her realize what was going on.

“I started seeing things on the show, which I didn’t know he was saying. Like, ‘I’m a dog with a leash,'” de Lesseps says, referring to a comment D’Agostino made to ex Missy Tool. “All of these things were hurtful, on top of the continued going out and still making the same circle, which I said, ‘Please don’t do that, because it’s not a good look for you.'”

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But the reality star knows her husband was always faithful.

“He assured me he wasn’t cheating on me, but that was not the perception of people around us,” she says. “We live under the spotlight, so you can’t act a certain way … you might be friends with your exes but it doesn’t look good. I believe he was not cheating on me. And I hope that was the case.”

De Lesseps’ Watch What Happens Live one-on-one with Andy Cohen airs at 11 p.m. ET on Bravo.