updated 10/22/2011 AT 5:00 PM ET
•originally published 10/22/2011 AT 6:30 PM ET
Happy birthday to Ryan Reynolds!
The actor, who turns 35 on Sunday, is celebrating this weekend with someone special: Blake Lively.
The Green Lantern costars – and their dogs – were spotted Saturday morning outside an apartment in Boston, where he’s filming the action film, R.I.P.D.
And this is no casual birthday meet-up. “They are very much a couple,” a source tells PEOPLE. “They’re really happy together.”