Something seems off between Sydney Sweeney and Jonathan Davino … her fiancé was just spotted in Los Angeles, after she’d been hanging with her girlfriends in town for weeks, then left the country without him — fueling speculation the couple is on the outs.

Jonathan was spotted Wednesday talking to construction contractors at Sydney’s $6 million Los Angeles mansion and taking a phone call.

Sydney went to France this week for Paris Fashion Week without Jonathan … and when she was in L.A. before her trip, she spent several weeks staying at the Beverly Hills Hotel without him too.

TMZ broke the story … Sydney stayed with some of her friends at the hotel and they gallivanted around the property for almost a month without him ever being spotted, sparking speculation about a potential breakup.

Keep in mind, Sydney and Jonathan were supposed to get married in May but, as we first told you last month, the wedding is postponed.

Sydney’s home being a construction zone is a pretty good reason for her to go stay at a hotel … but Jonathan not staying with her despite them being in the same city raises some red flags.

Plus, property records show the mansion was purchased by a trust Sydney has used in the past for her other estates … so this isn’t a house she bought with Jonathan.

It’s been a while since we’ve seen Sydney and Jonathan together at all … the last time was in January, so it’s been nearly two months at this point.