Word for pride of someone else's achievements

Is there a word or phrase to describe the feeling of pride directed at someone else's accomplishment?

In particular, I'm looking for a way to describe the feeling of pride of a romantic partner's achievements. Since these partners are neither married nor engaged, "spousal pride" (which might otherwise work) would be wrong.

However, failing that specific case, a more generic description is also welcome as long as it can be applied to this context.

Example sentence: A surge of wild _____ pride swept through him.

It’s pride by proxy. It’s a little hard to find a definition for this particular usage of the term, but there are plenty of examples of it in use. (It’s a figurative version of the “someone authorized to do something on another’s behalf” definition.)

It’s flexible in use. It can be used when the relationship is very close (as in your question), or even if the person you’re feeling the pride for doesn’t even know you (where the main connection is that you both fall into the same demographic).

For example, in a comment on the article Q&A and Cover Reveal: After Zero by Christina Collins:

Anyway, dont really know why i’m writing this, i guess its because im blown away someone from our tiny town is publishing her own novel and in a weird way im expiriencing some kind of pride by proxy…

And in this Goodreads review:

Yet the strength of women, sometimes, in this book, rejoices my heart, swells it with pride by proxy, a pride of being a woman, like Aïssatou who, after four children and a happy marriage made of love and of sharing, sees her husband yield cowardly to the family pressure, to marry a second woman, his very young cousin!

Perhaps vicarious pride?

vicarious adjective Experienced or felt by empathy with or imaginary participation in the life of another person.

from The American Heritage® Dictionary of the English Language, 5th Edition.

An obvious adjective, given the description, is romantic:

A surge of wild romantic pride swept through him.

However, that could be misconstrued as a pride of romance rather than pride of a romantic partner. So, it might not be acceptable.

Another possibility is paired.

From the noun pair:

[Merriam-Webster]
2 a (2) : a couple in love, engaged, or married
// were a devoted pair

Used adjectivally:

A surge of wild paired pride swept through him.

Again, however, an objection could be raised that this confuses pride being paired with something else (in its more traditional use as a verb), rather than it being his pride in his complement in the pair.

This variation is possible:

A surge of wild pair-pride swept through him.

It's a constructed term, but the meaning is clear—and it's exactly the meaning looked for.

I personally like pair-pride; however, it might not sound completely natural to some people.

If paramour didn't have a negative connotation and it had an adjectival form, it could work. Unfortunately, neither of those things are true.

It could be that there simply isn't an adjective that is completely appropriate in this context.

If not, the only option is to rephrase the sentence.

A surge of wild pride for his romantic partner swept through him.