My friends [19Fs] don't respect my [20F] relationship with my boyfriend [25M]

Throwaway because I know this is a petty thing to be writing about.

EDIT: This is not a post about the age difference between myself and my boyfriend, it is not the cause of any issues or concern between myself and my friends other than simply different interests.

I am a 2nd year university student living off campus with 3 of the girls I lived on campus with last year - I would consider these girls to be the best friends that I have at uni, and we usually have no issues with one another.

I started dating my boyfriend earlier this year when he was still a student at the same university we go to - he met my friends and there were no issues, however out of respect for both parties I tended not to mix the two too much due to a lack of shared interests mainly brought on by the age difference between myself and my friends and my boyfriend (eg. day out with boyfriend, movie night with friends), though this does not mean that we didn't all spend time together, such as games nights or meal times. There was however often the odd jibe from my friends about how they felt I spent a lot of time with my boyfriend, which they felt was at their expense.

At the end of the academic year my boyfriend's degree finished and he moved back home (over 150 miles from uni). Since the start of 2nd year I have been a lot more active in re-integrating myself with my friendship group, to which my friends have been supportive and pleased that I have been willing to do things that they viewed my boyfriend limited eg. going on a night out (he didn't, I would make the decision myself that I would sometimes prefer to stay in or at his instead of spending money on a night I wouldn't enjoy, something I have done already this year to no complaint).

Last night when we were all together one of my friends made a comment about another friend's new relationship as being the 'only relationship she cares about' - I did somewhat confront her and ask her if she had just forgotten if I was in a relationship, to which she replied that since my boyfriend is no longer here in the same town as us she doesn't view my relationship as 'real'; I was especially surprised by this as she had only just gotten out of a 3 year relationship that had mainly been an LDR. Another friend then mentioned that she feels the same as I apparently never mention my boyfriend (I do mention him occasionally, but I have no desire to shove him or my relationship down anyone's throats due to past criticism of the 'overbearing' nature of my relationship). I was hurt by this, though brushed my reaction off as tiredness because I didn't want to make a scene or have them interpret my mood as me being jealous of my friend being in a new relationship.

After sleeping on it I'm still hurt by the fact that my friends have switched from being overly-critical of my relationship for months to now not accepting the validity of my relationship for futile and unavoidable reasons; I am especially worried about how they may now act around my boyfriend when he visits in a couple of weeks. Would I be justified in asking them to affirm their view even though the discussion has been put to bed?

TL;DR - My friends/housemates have openly admitted that they do not view my relationship as valid since my boyfriend has moved away, however were critical of the time we spent together when we were closer, do I confront them about this?