Sydney Sweeney's Fiancé Seen Walking Her Dog Amid Breakup Rumors

Sydney Sweeney and Jonathan Davino seem to still be going strong despite breakup rumors ... as evidenced by her fiancé's latest outing with Sydney's close childhood companion.

Jonathan spent some QT Tuesday with the actress' dog Tank, taking the pup out for a walk. We gotta say, if Jonathan's worried about Sydney romancing her costar Glen Powell ... he wasn't showing it in his shades and athletic wear. Cool as a cucumber, this guy.

FYI, Tank has been in Sydney's life for years ... she adopted her 4-legged friend when she was a teenager. So, the pooch is definitely hers, and not JD's -- another sign the couple's still together.

It's further confirmation of what we first reported ... Sydney and Jonathan's engagement is still intact.

As you know, Sydney and Jonathan got engaged last year, but recently rumors started to swirl they might have called it quits -- a theory fueled by Sydney and Glen seemingly getting very cozy while filming a rom-com down in Australia.

And even after filming ended ... a vid of Glen and Sydney goofing off together recently went viral.

On top of that, the costars were at CinemaCon this week to promote their new flick, and were looking super into each other. Plus, Glen's GF Gigi Paris unfollowed Sydney on social media.

Our sources are shutting down the idea SS and GP are really an item ... making it clear all the flirting was just to pump up their movie.