I will write about the safety, how they would come to the point to speak and find a consent about it, is another point. I think we agree, that language and sharing thoughts is not the problem in different body shapes, but touching could be.

Option 1: make Mr Xurkesh less dangerous

Depending on the dangers that Mr Xurkesh offers,for example stuff the spikes with cork, place protective shields over the sharp parts, and never let him position above the Ms.

Maybe Ms. Smith has some dangers to offer too? Maybe her saliva causes skin rash in Mr Xurkesh?

Option 2: use/invite tools to help

The arms of Ms SMith are too short to reach a part of Mr Xurkesh safe? Use a telescopic tool to reach it.

The claws of MR Xurkesh are too sharp or too big to touch parts of Ms Smith? Use some small/soft tool with a handle, that gives MR Xurkesh enough control over it.

In conclusion you need to have an image (even in your mind) how romantic physical contact would be between intra-species-couples, and then try to find solutions how the "other" species could cause the same "happy feelings".

Depending of the characters (which I assume as open minded, because they came in close contact with other species) they may need planning for the solution, or may use improvisation to overcome appearing boundaries.

I will write about the safety, how they would come to the point to speak and find a consent about it, is another point. I think we agree, that language and sharing thoughts is not the problem in different body shapes, but touching could be.

Option 1: make Mr Xurkesh less dangerous

Depending on the dangers that Mr Xurkesh offers,for example stuff the spikes with cork, place protective shields over the sharp parts, and never let him position above the Ms.

Maybe Ms. Smith has some dangers to offer too? Maybe her saliva causes skin rash in Mr Xurkesh?

Option 2: use/invent tools to help

The arms of Ms Smith are too short to reach a part of Mr Xurkesh safe? Use a telescopic tool to reach it.

The claws of MR Xurkesh are too sharp or too big to touch parts of Ms Smith? Use some small/soft tool with a handle, that gives MR Xurkesh enough control over it.

In conclusion you need to have an image (even in your mind) how romantic physical contact would be between intra-species-couples, and then try to find solutions how the "other" species could cause the same "happy feelings".

Depending of the characters (which I assume as open minded, because they came in close contact with other species) they may need planning for the solution, or may use improvisation to overcome appearing boundaries.