Ryan Reynolds and Blake Lively Are Dating

Blake Lively and Ryan Reynolds
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.”

Lively, 24, recently split from Leonardo DiCaprio after a summer romance, and Reynolds is still friendly with his ex, Scarlett Johansson.