New Rose Bush Doing Badly

Good morning @LuckyTurnips and welcome my friend ,I would say it looks like the soil ,the roots don't like it,it hasn't been pruned correctly,try the finger nail test just lightly scrape some of the canes to see if they are green underneath,if it were my rose I would cut it back tidy it up and then re-pot it using John innes No 3 just my opinnion of course.

If you need any advice or questions answered just ask my friend

Lets ask ourselves some questions
1.Has the container got holes in the bottom to allow adequate drainage
it should be raised from the ground little
2,Is your Rose planted firmly
3.how much sun in hours does your Rose get per day
4.what is the size of your container
5.Are you feeding it to much
6.It could be overwatering

Scentimental
Floribunda. Red, white stripes. Flowers striped burgundy and white, or cream, or red, opening quickly. Mild to strong, damask, rose, spice, opinions vary fragrance. Large, double (17-25 petals), cluster-flowered, in small clusters bloom form. Blooms in flushes throughout the season. Height of 35" to 47" (90 to 120 cm). Width of 31" to 43" (80 to 110 cm). Tom Carruth (1997).

 

Good morning @LuckyTurnips over time soil and conditions change,when you get a pair of new shoes they feel fine a month later they are uncomfortable and you can't walk in them