Elsie Hewitt Celebrates First Mother's Day Solo Amid Pete Davidson Rift

Elsie Hewitt just celebrated her first Mother's Day ... but there was one thing missing from her emotional Instagram post -- Pete Davidson.

The model posted several pics with her daughter and her life as a new momma ... with the caption "We're all here because of a mother's sacrifice to make herself your first home. I got to be Scottie's❣️Greatest honor of my life. Happy Mother's Day 💐🌷🌼"

Pete was working on the other side of the country ... in Los Angeles, among those present at Netflix's "The Roast of Kevin Hart" ... but still, the optics aren't great amid the duo's rocky time. Plus, comics took a lot of shots at Pete over his infamous dating history -- probably not something Elsie wanted to hear on Mother's Day.

As we reported earlier this month ... Pete and Elsie are going through a rough patch in their relationship, five months after welcoming their baby girl, Scottie Rose.

Sources familiar with the situation tell TMZ ... the pair is dealing with some challenges, but they're trying to figure things out together. We're told they’re working through a difficult time and sorting out what direction their relationship is heading.