Saturn square pluto is common, effective I wouldn't say the biggest of worries here. Saturn square Ascendent is more important and it says exactly what you describe having tight criteria on de behaviour of the other person .. like when you seeing him beigh too flirtatious.
I am not completely sure, but it seems to me that your sun/moon midpoint is conjunction his moon and his s/m is on your sun .. or close to it. That is very positive for any relationship.
