I used to get that too - that strange look and apprehensive attitude crew of other airlines sometimes initially give off until they realise you are just a normal person in a different uniform.
We used to have long turnarounds in one port, where our crew would normally eat the crew meals. It was not uncommon to have crew from 2-3 other aircraft come join us for a chat, something to drink, and perhaps some food if there was enough to spare.
For most, the only difference is a lifestyle choice.
DJ - plenty of opportunities to do overnights
JQ - limited/no opportunities to do overnights
It all comes down to the individual - lots of overnights suit some, being home every night suits others. There will ALWAYS be those who would rather the lifestyle the other airline presents, as such there will always be those jumping to the other team. Single digit numbers of crew applying to jump across at an interview is far from anything major!